When writing a song, you can pretty much take it in any direction you want to. As much as it might get old singing about the rock and roll lifestyle, the best kind of tunes always come from a personal place, where artists reach deep in their souls to find a part of themselves they had lost along the way. This is the world of sex, drugs, and rock and roll though, and that second one has definitely had a hand behind the scenes more than a few times.
Throughout every single genre of rock, there have been albums that were written solely under the influence of drugs without anybody even noticing. While it might not be explicit in the lyrics or anything, you can tell that these records were...let's say "chemically altered" from the word go, whether that be because of the overblown production or just the overall haze that it puts you in.
That doesn't mean that every album on here is necessarily dreadful. Outside of the drug references, these artists managed to make songs that stand out apart from their vices, looking to either write these songs as a warning to their fans or spinning them into something completely different by the time they finished. Because anyone can just get messed up and try to play their guitar, but it takes a true musician to make actual art out of a bad situation.
10. Korn - Korn
There's no way of copying the sounds of Korn's debut. Being ground zero for the sounds of nu metal, this was just the result of the band getting as heavy as they could while Jonathan Davis poured out his inner torment on every single track. If you want an answer to why it sounds as dark as it does though, the answer is meth. A looooot of meth.
When Davis looks back on this era of the band, this is around the time where he was really strung out on the stuff, and often ended up putting that kind of imagery into every single song that he sang. As much as it shouldn't work, the paranoia that comes with being out of your mind actually helped a lot of these songs, giving you the impression that Davis was like a patient that had been locked in a mental institution before deciding to start a nu metal band.
In the years since then, Jonathan has said that he has gotten clean from most of the stuff, with his vocals during the later years getting worse and worse because of him being messed up when it came time to track the songs. In that respect though, Korn's debut isn't just another dark as hell metal album from the '90s. Considering the massive amounts of crystal that came from this, it's a lot more violent and disturbed than you probably gave it credit for.