I just had a brilliant conversation with Sam Snyder - extremely smart guy.
We talked about a lot of things, and a few stood out to me - he clued me into the notion that many internet trolls might actually be mentally ill.
It's like, how bad off do you have to be to get satisfaction out of blogs, social news sites, and discussion forums? Pretty bad. As Sam put it, "Bad enough that you can't even get satisfaction out of playing video games."
More interesting, though, is that Sam introduced me to the concept of "emotional contagion" - by getting exposure to others' emotions, you frequently start to feel those emotions too.
So when you deal with people who are hostile and off-balance, it can make you a little more hostile and off-balance yourself. Scary stuff.