Separating the art from the artist is always a good idea. It doesn’t really matter to me that Patrick Wolf is actually a bit of a whiny bullying jerk, as I don’t socialise with the chap. So all I care about are his records, which are sublimely wonderful. Equally, that Billy Bragg is plainly a diamond geezer won’t ever make his songs anything other than agonisingly dull. So when sitting down to listen, even to us lovers of the visual and conceptual fripperies of pop, it is always, to some degree, all about the music, man.

However, the wholly unparalleled levels of fame and forensic media scrutiny of Michael Jackson makes this an altogether more difficult endeavour in his case. The toxic miasma of unnerving fact, myth, rumour and half-truth around the squeaking monkey-lover has been so all-pervasive over the last 25 years or so, probably only a recently-awaken coma victim could really give this compilation a truly impartial hearing.

The murkiest area of the Jackson story - the two separate child abuse allegations, first 1993 and then in 2004 - is also the one that dominates most contemporary discussion of the man, but we're trying to review a CD here, so let's get that out of the way and move on. It remains fact that no charges were brought in the first case, and that Jackson was acquitted in the second. So if you believe in the principle of innocent until proven guilty, the matter really has to be left there.

However, even putting all that aside, the Michael Jackson story is still a distressing, weird and ultimately rather tragic one. Born in 1958, he was the seventh child of Joseph Jackson, a frustrated musician and classic pushy parent who had already alternately encouraged and harangued Michael’s older brothers into becoming a tight stage act while Michael was still a baby. Michael soon proved to the family's true prodigy, though. displaying astonishingly mature dancing and singing skills almost as soon as he could walk, joining his brothers by the age of six and becoming the group's on-stage focal point by the age of ten.

As is now common knowledge, Joseph was an extremely tough manager to the nascent group; certainly violently abusive by his own admission, and sexually so in Michael’s sister LaToya's account, (though this remains a matter of some debate, with not even LaToya herself maintaining a consistent position on the matter).

Whatever actually went on in the Jackson home, Michael is on record as saying he found his father's mere presence so intimidating that it would cause him to both vomit and faint. So not, on the whole, an idyllic childhood and one where pressure to perform on stage was the frequent flashpoint of a troubled parent-child relationship.

Still, up until his mid-late 20s, Jackson's talent seemed so vast as to magically elevate him above such grubby concerns. His was the voice that expressed pure joy in the groups Motown hits such as 'ABC' and 'I Want You Back' in the 60s, the physics-defying dance skills that brought the world "The Robot" in the 70s, and the remarkably forward-looking multi-media pop vision that redefined the music business in the early 80s. It's apparent now that this comet-like blaze was pop artifice at its most brilliantly executed, and behind the multi-million dollar videos and glorious sheen of his recordings was a lonely and deeply troubled individual, growing increasingly distant from his family and few friends, holed up Howard Hughes-style at his Neverland ranch, with just his money and his monkey for company.

So, er... separating the art from the artist, then. What's easy to forget about Michael Jackson is that he was, no question, one of the greatest pop talents of the 20th century. Already forging ahead as the lead singer and songwriter in the Jacksons (after they left Motown and dropped the "Five" from their name), he started to dominate the group on their 1978 album Triumph. Triumph's hit single 'Can You Feel It' pointed directly to Jackson's imminent solo career, with its sonically modernist take on disco and then state of the art promo video. Shortly after this, while playing the part of the Scarecrow in a bizarre blaxploitation remake of Wizard of Oz called The Wiz, he formed an alliance with that film's musical director Quincy Jones, who agreed to produce a solo album.

Which is where this compilation picks up the story. “King of Pop” is what the tabloids used to call Michael before they settled on the rather less flattering “Wacko Jacko” around 1983, and re-appropriating that sobriquet for a retrospective is to make a bold claim that in places, the tracks here back up convincingly well. Opening with 'Billie Jean' is a killer move, as it’s probably the track in Jackson’s repertoire that most lives up to the billing. I’ve heard it at weddings, I’ve heard it in hipster clubs full of kids with triangular haircuts and I’ve even heard it once at a crusty rave back in the late 90s. I’ve never seen a dancefloor not go completely wild for it, and it still sounds astonishing today, prowling like a panther and featuring one of Jackson's last truly great vocal performances before the squeaking and gasping became self-parodic.

Of course, some of this is attributable to Jones, with whom Jackson collaborated intensively from 1979’s astonishing breakthrough Off The Wall LP up until 1987’s cracks-starting-to-show Bad, and there’s no question that the Jones tracks beat absolutely everything else here hands down.

The first disc is drawn mostly from the Quincy years, and is pretty much unassailable. Sure, Thriller, Bad, and Smooth Criminal all mine the same somewhat daft let’s-inexplicably-remake-a-movie-genre-in-the-form-of-a-pop single seam, with increasingly silly results, but they are all propelled along by brutally hard and nasty funk rhythms. And anyone who doesn’t think 'Wanna Be Startin’ Somethin’' is the most bad-ass dance record of the early 80s is simply wrong and probably a eunuch.

Whoever has compiled and sequenced this collection has wisely avoided strict chronological order, which would have positively begged the listener to indulge in a bit of hobbyist psychoanalysis. Unfortunately, the differences between Jackson at the top of his game in the late 70s to early 80s, and Jackson in steady artistic and personal decline for the following quarter century are so stark that uncomfortable contrasts are almost unavoidable. 1991 single 'Black or White' is fired like a cannonball into the middle of the Quincy Jones pop-funk battleship of the first half hour, and almost sinks it like the Titanic.

This is where the art / artist thing gets tricky again. 'Black or White' opens with an overlong section featuring a teenage kid playing records in his room while an angry parent bellows through the door for him to turn it off. Given what we know about Jackson’s early life, it’s nigh-on impossible to read this as a jokey skit; as with many of Jackson’s later records, it comes across as a desperate need for self-revelation, but one that sat awkwardly in the glittering pop edifices he constructed.

And while 'Black or White' is a sparky enough slice of pop, the lyrics of the chorus raise the issue of Jackson’s increasingly pale appearance. If you’re thinking of being his baby, Jackson asserts, it doesn’t matter if you’re black or white. What he fails to add is that he’d by this time decided that he was going to be white.

And this is what is inevitably discomfiting about this (and probably any) compilation of Jackson’s work. Unless you're one of the diligent superfans who jealously defend the Jackson Wikipedia page with relentless on-message edits, making his entry a weird stroll through an alternate world of press-release hyper-credulity, where his shrinking nose and Caucasian skin tone are tricks of the light and nothing to do with surgery, the clash between what you're hearing and what you know about Jackson is frequently uncomfortable. Or ludicrous, depending on your perspective.

However, after that jolt, disc one regains it's stride, with 'Don't Stop Til You Get Enough''s sun drenched pop-funk and 'The Way You Make Me Feel''s synth-pop update of the classic Motown sound both remaining entirely irresistible. Even the weaker songs from this period, such as the fairly conventional smooth R&B of 'Rock With You' and the Kids-From-Fame rock-funk of 'Beat It' have aged remarkably well.

Unfortunately, what this compilation reveals most cruelly is how quickly these glory days were over. Jackson's second solo album proper, Thriller (he'd recorded a few novelty albums as a Motown child star, which needn't concern us here) is the biggest selling album in recording history, having notched up well over 100 million sales. This success sent Jackson into a creative tail-spin, determined to top the success of Thriller, but fatally trying to do it by creating ever more faded Xeroxes of that album.

Follow-up album Bad gets more or less as many tracks as Thriller on here, but the self assurance of the previous two albums is already disappearing. 'Dirty Diana' is a confused lumbering slog of a song, an attempt to both recreate the pop-rock alchemy of 'Beat It' and out-sleaze his contemporary Prince. Jackson was never convincing in this kind of role, a boy-child trying to write a song about the kind of woman he never meets in the kind of places he's certainly never been to.

His unbearable post-Live Aid "heal the world" shtick" started to appear on this album too, with the execrable 'Man In The Mirror', solipsistically suggesting that "if you wanna make the world a better place", then all you need do is "take a look at yourself, and make a change". But without wishing to be unkind, Jackson is hardly a good advert for the merits of narcissism.

After this, the gems are lamentably thin on the ground. Some more Quincy-era killers are scattered throughout disc two, just about rescuing it from being re-purposed as a coaster. 'Off The Wall' is downright essential, and even his collaboration with Macca, 'The Girl Is Mine' is not without charm. But Jackson only really made one more serious effort at an album after Bad, 1991's Dangerous featuring the then-hot-but-now-horribly dated New Jack Swing sound of producer Teddy Riley. 1995's HIStory is a hits compilation with a few new tracks dropped in, and 2001's Invincible is so-swamped with "co-writers" and guest stars you can barely make out Jackson at all.

More troubling than the drop in musical quality, though, is the attendant rise in lyrical and conceptual weirdness. HIStory's lead single 'Scream' is featured here, and as a howl of fury at the world's press for their reportage of the first round of child abuse allegations, it remains a deeply disturbing listen. Arguably, libidinous rock funk with Nine Inch Nails-style noise bursts is not the most appropriate medium for addressing the concept of media fascination with pederasty. And 'They Don't Care About Us', with it's highly dodgy "Jew me / sue me" lyric is barely less palatable. The tracklisting was voted for by fans apparently, so somebody's getting what they want here. But this stuff is not for the casual listener, and I don't mean that in a good way.

However, at least these tracks have a bit of vigour about them. Jackson’s latter-day output is increasingly dominated by instantly forgettable ballads like 'You Are Not Alone' and 'Stranger In Moscow'. Can’t bring it to mind? No, me neither and I’ve just listened to it twice.

King of Pop has already been released in both one and two-CD formats, and the major bulk added on this new three-CD edition is in a third disc mainly comprising wholly unnecessary remixes and a hideous "Thriller Megamix", which mashes most of that album's tracks together in the timelessly awful style of Jive Bunny and Stars on 45. If you're too young to know what I'm talking about, thank your lucky stars, and don't throw away the privilege by subjecting your ears to this tosh.

So, which version should you buy? Well, you shouldn't buy any of them. Save yourself from the long second disc meander through his back pages that manages the unusual feat of being both thoroughly disturbing and a bit boring. To get the good stuff, go and buy the Off The Wall and Thriller albums and a good Jackson Five compilation, and marvel at how incredible Jackson was before dysfunction consumed both him and his talent.