Another one I've found recently are these fashion forums populated by 90% females. I found them by accident looking for pics of Natalie Portman (sue me), and they have ~300 page threads on every major celeb, commenting on every different outfit and hairstyle they wear, slagging them off etc. and generally posting worthless ****. They all have pics of amazingly hot women as their avatars, I'm betting 1% are their real photo, 99% are probably butter trolls in real life. I wanted to reach through the screen and punch them. You thought male-only forums were bad? Think again.
Oh, also I tried to sign up to troll them, and the site is invite-only and there's a waiting list LMAO, like they're pretending to be some exclusive club. :/