I saw Nine Inch Nails for the first time at Reading Festival in 2007. It was my first UK festival experience, and the last for a long time. I went just for the Sunday, not realising that this meant walking into a three-day-old reeking expanse of adolescent waste. Some brilliant entrepreneur in the melee was peddling watermelon slices with the rind on to sun-soaked, electrolyte-deprived teenagers who proceeded to throw their scraps down in the dusty paths. This must have been going on all weekend, judging by the horrid rotting fruit smell that permeated the campground, but didn't seem to perturb the weekenders in the slightest. That rank odour, mixed with the smell of beer (also entrenched in the soil for the square mile) and the odd faint whiff of vomit, made for a particularly rich and repugnant stench. The day continued in a similarly disappointing fashion, with lukewarm sausages of a grayish pallor for lunch and terrible sound quality from most of the stages. Band-of-the-moment Klaxons were far too big for their tent and dozens of people were turned away. I was ready to hightail it back to the Big Smoke by the time Nine Inch Nails appeared on the main stage.

Coming on after an as-yet-unscandalised Lostprophets, with the daylight still lingering, Trent and co ripped into 'Hyperpower!' accompanied by an appropriate amount of strobe-lighting and smoke. Now I know this is far beyond the early days when their live shows involved band members lumping the stuffing out of each other, but it was an invigorating experience nonetheless. In particular, the end of the set managed to turn the whole day around in an instant. Alone on the stage bathed in black with a starry landscape cascading over him, Reznor breathlessly uttered the first lines of 'Hurt'. The crowd roared then quickly hushed. With the building of the verses and the radiating elation of that stinking mass of mucked up teens, a ballad of drug-addled self-loathing became anthemic and beautiful. From his empire of dirt to theirs.

Crafting discord and filth into beauty, and vice versa, has always been Reznor's talent. I don't think any Nine Inch Nails record shows that quite as perfectly as The Downward Spiral. It's a harrowing experience right from the beginning - if 'Mr. Self Destruct' comes over my headphones while I'm out and about, I will have to quickly fumble for my iPod to turn down the volume. When the THX 1138 sound clip of a prison guard punching gives way to the first of many intense bursts of industrial cacophony, it never fails to make me wince. The whole album has an array of terrifying and confusing sounds that make for an unmatched listening experience. 'The Becoming' could be a soundtrack to parts of Dante's Inferno. Is that an angry hornets' nest or whirling machinery on the title track? Angular yet pleasant melodies cut through the metallic grinding all over the album, but a lot of it is genuinely hard listening material. It's also intensely personal, documenting the delusions and depressions of long-term drug abuse as well as dark unquenchable lust. The album's evocation of these powerful feelings led many a critic to announce it as autobiographical.

The lyrics are pretty open to interpretation, but it does appear to tell a story. It could be an addict's descent into madness, losing religion ('Heresy') and love ('The Becoming') along the way. Or, it may be about a self-loathing narcissist's use of sex ('Closer') and violence ('Big Man With A Gun') to take power over everything in his life before realising the damage of his abuse ('Eraser'), and taking his own life ('The Downward Spiral'). It could even be a combination of the two or none at all, but there is a lot of anger, mania and sadness in whatever the protagonist is experiencing. Either way, the album closer 'Hurt' is obviously an expression of life-long regret. So personal is the song that Reznor compared hearing Johnny Cash's tear-jerking cover of the tune to "seeing someone kissing your girlfriend".

What is easily forgotten here is that Reznor was really pushing the boundaries, he was creating new sounds that would not fit into recognized emotional associations and he was doing this before the days when any floppy-haired goth could punch it out on their iPad. It does seem almost a shame that these effects are so easily reproduced these days, leading to legions of diluted and passionless NIN imitators.

Beneath all the noise, however, are some excellently crafted pop tunes. 'Piggy' and album single 'March Of The Pigs' are, for different reasons, both proof of Reznor's gift for a tasty hook. He showed this off on Pretty Hate Machine as well, but here he seems to have taken the pop sensibilities from influences like Depeche Mode and turned them into something darker and dirtier and, most of all, wrenched right out of the 80s. An incredible thing about listening to this album in context is how well it holds up in comparison to its contemporaries. Also celebrating a twentieth anniversary currently is Soundgarden's Superunknown, which happened to be the only record that kept Downward Spiral off the top of the U.S. charts when they were both released twenty years ago. Possibly owing to the clarity of Reznor's production, it's mind-blowing that these are from the same decade, let alone the same month – Superunknown sounds so 'retro' in comparison. It's no wonder that David Bowie took a shine to young Trent and his groundbreaking, obnoxious noise.

The recording process itself was also notable because at the time Reznor was renting 10050 Cielo Drive in Los Angeles, where the most famous of the Manson Family murders took place. Though it was over twenty years since Sharon Tate and her house guests were so brutally slaughtered, it was still quite a big talking point when Reznor took up residence and built Le Pig studio inside it. He later admitted that naming the studio after the word once scrawled in blood on the front door was in particularly bad taste, but would also take said door as a souvenir with him after leaving the property.

It's hard to say why he would do such a thing without much consideration over why taking up residence there was a controversial move. I do believe that Reznor was genuine in saying that it wasn't for press, but rather out of simple curiosity about 'American folklore'. Pretty Hate Machine had seen the band getting big in a "strange way" according to Reznor. And always much more the anti-star than any others at the time, he was all about satisfying himself over anyone else. In fact, Reznor went about creating angrier and angrier music with noise of escalating, clanging terror and bitter dirge. He seemed bent on creating something totally non-commercial and even went so far as taking the catchiest song on the record, 'Closer', and turning it into something nigh on impossible to get on the radio. He also accompanied it with a disturbing video showing bondage, nudity, a monkey tied to a cross and various bloody and disembodied animal parts. But to his own detriment/fortune, Reznor couldn't hide his own melodic skills and 'Closer' became his biggest hit up to that point (not to mention the heaps of praise that the video has received over the years). With this in mind, it's actually quite comical to watch him lament in interviews about 'not doing enough' to keep from getting so big.

But if I were Reznor I wouldn't regret a thing – except maybe the whole Tate house fiasco – as The Downward Spiral remains a dynamic and layered work that offers more at every listen. Though it takes time for some to fully appreciate it, its varied textures and moods make it both a staple and subverter of industrial music. The melodies are actually very accessible, once accessed; you just have to wade through and learn to appreciate the noise, distractions and overall dirt around them. Just because something jars your senses, be that thundering dissonance or the smell of 70,000 kids not giving a shit, it doesn't mean there's no poignancy and meaning behind it.