These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Anyone drawing/writing hide/anyone in or before 1998 or Taiji/anyone in 2011 with anything set Twenty Minutes In The Future or otherwise not an alternate universe, due to the deaths of both. The existing stuff presuming them to be alive reads in a very jarring way. Now both aren't abandoned, but written either as alternate universe or back when the person written about was alive.
Toshi/Kaori, for very obvious Real Life reasons, so bad that writing it now in any favorable way is trolling.
Yoshiki/Miyavi, when Sugizo was picked for lead guitarist and Miyavi got married - the shippers either dropped it out of respect for Miyavi and/or his marriage, and/or because it became a lot harder to use a lot of standard bandslash plots, though it will still occasionally pop up as a joke.
Base Breaker: There have been more than a few, which is part of why the fandom tended to have raging Flame War on a regular basis whenever it becomes active. Here are some of the more notable ones:
The very first was probably the decision to incorporate ballads such as Endless Rain. Eventually, this split the fandom in three directions: fans who preferred the Hard Rock / Heavy Metal / Thrash Metal, fans who prefer the ballads, and fans who like both. Most coexist fairly peacefully, however, though occasionally hardcore metalheads and ballad-only fans will wage flamewars. This was also an internalBase Breaker as it was the very first issue that drove a major wedge between Taiji and Yoshiki, per both's autobiographies.
The decision to replace Taiji with Heath - which led to Taiji fans, Heath fans, and the very rare fan of both - and often, all engaging in protracted Flame War over who was the best of the two.
The slow move away from Heavy Metal / Thrash Metal to Gothic Metal / Gothic Rock and industrial music, culminating in Dahlia, which is itself a Base Breaker - depending on who you ask, it's either the band's worst album ever, or the most innovative album showcasing everyone's individual talent.
The band's disbandment in 1997 and who was technically to blame the most led to a massive split between Toshi fans and hide fans, that often fed into the Die for Our Ship flamewar as well, and even when it didn't, especially after hide's death, made hide fans hate Toshi for a long time, and vice versa.
The band's reunion - some fans hate that it reunited at all, others are happy it did.
The use of hide's imagery and music after his death: some fans see it as a tribute to him, others hate it and see the band as too hide-focused, others now hate that Taiji isn't getting equal tribute time...
Sugizo having been chosen as the new lead guitarist. There were and are partisans for everyone from Richard Fortus to Kaoru of Dir en Grey to Miyavi to Sugizo himself to hide backing tracks, and all will happily argue over it.
Yoshiki doing more solo work and delaying the album is becoming a new split - fans who are happy to see Yoshiki taking a new career direction and Yoshiki fen in general versus fans of the other members and of X as a whole but who aren't specifically Yoshiki fans or who are even Yoshiki haters.
Crack is Cheaper: Unless you are as rich as Yoshiki is, do not try to collect every bit of X Japan merch, ephemera, go to every single event possible, get every release and every box set and everything they've ever done. You cannot do this.
Averted, however, with shows and events outside of Japan where the tickets are well within reasonable range, especially for Yoshiki solo classical shows but even for the full band - 2010 World Tour tickets in the US were $60 for general admission and $80 for pit on average, which is actually very reasonable for a band of their caliber (as a comparison, expect to shell out a fair bit more for Guns N' Roses or Mötley Crüe or Kiss) and many of Yoshiki's events/appearances in the US are even free to attend aside from travel and lodging costs (which, admittedly, can hurt for Los Angeles where most of the free events are, but if you live there already...)
Crowning Music Of Awesome: The 29 minute long (33 minutes when performed live) Art of Life, which went from gentle ballad to heavy rock to twelve-minute long piano solo and back again. The song, which was years in the making, tells a very clear, powerful story of someone pulling themselves through a BSOD.
It's Yoshiki's autobiographical story to that point. The BSOD was, according to the Art of Life DVD insert, his physical and mental collapse from "neurocirculatory asthenia" in the early 1990s, which was likely either severe unipolar or bipolar depressive disorder, and/or the beginning of his thyroid problems combined with his other health issues.
"Alive", despite only being performed live twice is widely considered to be among the band's top ballads, mainly because of Toshi's extremely emotional vocal performance, and the song's guitar driven nature, which is opposed to most X japan ballads having piano has the driving instrument.
Dude, Not Funny!: There's two things not to joke about around anyone in the fandom, and those would be hide's or Taiji's deaths.
Claiming someone else in the band has gotten seriously ill/injured or died is the other big one. It's both trolling and a trigger, especially for people who experienced the pain of learning about the other deaths, and knowingly creating a death rumor is one of the very worst things you can do in the fandom.
Epic Riff: "Kurenai," "Art of Life," "Blue Blood," "Silent Jealousy."
Pata, because he was always and is still the more quiet and reserved of the band's guitarists onstage, despite being more skilled than either hide or Sugizo in some ways.
Heath, because he's also fairly quiet (or at least was before his return to full Visual Kei style), and because a large chunk of the fandom does see him as a mediocre replacement for Taiji, yet an equally large chunk of the fandom are fans of Heath for either his looks or style or even his musical skill. So where few people will say Heath is a better bassist than Taiji (unless they want to be flamed by angry Taiji fen) he does have a surprisingly large fandom.
Everyone Is Jesus in Purgatory: "Week End" (an allegory for suicide and the "end of the world" as the "end of a life"), Rose Of Pain (Elizabeth Bathory), the 1994 anime Rusty Nail PV (cue jokes about Yoshiki's Messianic Complex that persist today, never mind he doesn't have one).
Family-Unfriendly Aesop: Obviously there's a few of these lying around, both in the lyrics and in the actions, especially in the early days.
Fan Myopia: The band has a very difficult time balancing between trying to please and provide fanservice to its current fans (especially since they are an eternally Broken Base and Unpleasable Fanbase due to that) and draw in new Western fans. They often lean more toward the former, which can cause the latter to immediately write off the band and its fans as anything from incomprehensible inside baseball they don't get to a cultlike odd organization of weirdness to, if they're of the homophobic Fan Dumb variety, "fucking gay."
Have they sold out or not? This one is almost pure Fan Dumb vs. Hate Dumb when it starts.
"It was suicide!" in regard to hide OR Taiji is a way to invoke Internet Backdraft and often start a massive Flame War at the same time. (For hide, because his death may well have been an accident and/or the result of neglect, and for Taiji because his death was most likely homicide written off as suicide.)
Jumping the Shark: There are a wide range of beliefs on when or if the band has done this, and whether it's for good or not. That said, whether it's for good or not is debatable - after all, the 1997 disbandment seemed to be final once hide died...
Harsher in Hindsight: Taiji was the only one whose character was murdered in the Week End PV, with the others' characters dying of suicide. In Real Life, his death was actually most likely murder covered up as suicide.
LGBT Fanbase: In Japan and in the west, as a result of everything from the copious amounts of man on man fanservice, the ballads being open to either gender, the possible bisexuality of some of the members, their 1990s HIV/AIDS activism, and more. Also, the costuming and personas and appearance, at least for 1987-1992 era, ran almost the spectrum of appeal to gay/bisexual men - for those who found androgynes or twinks appealing, Yoshiki was the "neko" or "princess," while at the same time subverting those tropes and the "innocence" side of The Twink wildly, and hide was so androgynous as to somehow reach the point of Ambiguous Gender (which also earned a small amount of a transgender fanbase for hide). Meanwhile, for those who preferred more manly, there was Taiji, the well-endowed Badass Biker cowboy, Toshi with his Hell-Bent for Leather look and dominant behavior, and Pata who was The StoicShrinking Violet.
Lowest Common Denominator: Especially with the early lyrics and album cover imagery, taken entirely at face value the band could be seen as playing to this, and yet on some levels it was, yet on others, the symbolism and meaningfulness made even the attempts to play to the lowest common denominator take on some sort of artistic value or intelligent commentary (usually, although sometimes, like with the Vanishing Vision cover, they just seemed gratuitous). Some of the most interesting things about the band are its use of Fridge Logic and the Genius Bonus lyrically, symbolism where anything could mean something more and also could not in performance and art, and Lyrical Dissonance so that while it plays at this level, there's many other levels for the interested or more intellectual to explore.
Most Annoying Sound: The 1993-2011 live concert intro that consists of "X Japan Japan Japan Japan Japan Japan Japan..." which is even more annoying when seeing a show, because unlike YouTube, Real Life doesn't have a mute button.
The cover of Vanishing Vision is an absolutely vile depiction of a rape. There is nothing redeeming it and no reason for it to have been used as the cover art, and the implication that rape is "sexy" often gives people who see this Old Shame before anything else a very bad image of the band.
The Monster Misogyny of Sadistic Desire gives it boatloads of Unfortunate Implications regarding misogyny, rape, and murder of women, even if the narrator is likely a Villain Protagonist and the song is a clumsy attempt at proto-BDSM by kinky people just discovering themselves and not knowing the "right" way to express kink just yet.
Celebration band version Performance Video is a more innocent case: at the time it was written in The Eighties, it carried a message of rebellion against authority and was a retelling of the Cinderella story. The only problem is it featured a girl barely 13 as a fan of the band, who went out for a night on the town with five bandmen known for "sexy scandal" while her mother who was trying to protect her from their bad influence was paralyzed... accidentally invoking both Fridge HorrorAdult Fear, And I Must Scream, and making the band easilyMistaken for Pedophile to modern viewers of the video (who don't get that the girl was treated as a friend in the PV with no one doing anything troubling to her)
Dahlia's PV has the issue of being straight-up horror and casting a protagonist who is either underage female or Dawson Casting with an adult female. It borders on Monster Misogyny and would be it if not for a few tweaks that make it not such (though still not something you'd likely want to watch at work).
In a more meta sense, the band's meteoric and ongoing success despite being known most for Sex, Drugs and Rock & Roll and the Bar Brawl early on, and complex interpersonal entanglements and intense internal drama later on, and despite the bandleader taking 90% of the income from the band, and despite almost all of the members having almost proudly untreated addictions and mental illnesses until hitting their 40s and some even still then. A lot of fans don't realize that their success was actually and is actually impeded by all of these things as much if not more than it was made by them, and the band has been Blessed with Suck and Cursed with Awesome and has had huge doses of incredible luck and fortune (and even with all of that, two of its members have died awful deaths - one from accidentally killing himself during a drunken sex act, the other from likely homicide). In other words, when it comes to copying their formula for success, definitelyDon't Try This at Home. Being responsible and safer with alcohol and drugs (and seeking help if you even think you are addicted or are in danger of becoming addicted), avoiding unnecessary conflict and violent conflict with others, equitably sharing funds amongst band members, seeking help and care for physical and mental illnesses, keeping communication open with everyone in any given situation, and being prosocial is essential to ongoing success and less drama for a band.