I've come to the conclusion that at least 1% of users are actively malicious with at least enough free time, resources, and coordination of a small full time team of professionals. I created and hosted a free self-moderated community which went well for a little while, until at least a couple people became obsessed with spamming the site with extreme gore (see the Mr. OP comment in http://old.reddit.com/r/editfight which is relatively tame compared to other things they've done) and evading every single method I had of stopping or banning them, until I had to just give up altogether and shut the site down. I feel bad for the moderators on imgur.com (where I got the majority of my users) because I read somewhere that many of them now have to go to therapy for some of the things they've seen in doing their job. Online communities and the moderation of them in the modern internet is problematic enough that I personally never want to tackle that again, not even by delegating it to someone else.