This is purely based on my own experience but the only kpop fans that are genuinely nice are casual listeners, mainly because they listen the music casually and form no personal attachment to the actual group or idol so will rarely get shady over idols.
If you consider yourself to be a stan, you've probably developed a personal relationship with the group/idol where you'll sacrifice your family to lucifer in order to defend your faves (joking...kind of).
Even the ones who act like they're nice to preserve their AKP image...I just know y'all secretly like this when you talk good about groups/idols you don't follow: