I think derogatory labels are bad in general .. But!
Let's all admit that there are some pretty creepy people out there. Like, seriously, they freak me out .. people that have wrapped themselves so tightly into their hobbies and this personal reality based on fiction that they then overlay that over real life. It's not like I can't intellectually understand the logic of it -- considering how dull ordinary life can be perceived to be, getting enjoyment and stimuli (of all sorts..) from entertainment is all well and good, barring the fact that people can slip and fall into a trap where these fictional realities feel less real than their real lives..
tl;dr -- Everything in moderation. Calling people names is bad.. however if someone calls you a name -- you should self-reflect to make sure there isn't a reason for it.