Hmmm. I think it does depend somewhat on the general maturity of folks who are likely to be attracted to a certain fandom... I mean, teenybopper-attracting fandoms are likely to be worse, I would think. Also the age of the fandom -- I mean, if a fandom is 20 years old, then everyone's already had their flame wars and gotten over them... (yes, I have a couple of fandoms in mind when I say this...)