Riot Games has found that in the League of Legends community, bad behavior comes mostly from people who are generally good. The problem with the LoL community isn’t that there’s a few jerks who spoil things for everyone; it’s that a lot of people act like jerks occasionally.
This factoid comes from a talk by Riot showing statistics from their player community. “Toxic” means raging during an online game, insulting and threatening other players. They use the word “toxic” because they’ve found bad behavior is contagious. One person acting badly can make other people angry, who then act badly in subsequent games. Dangerous problem.
That finding has all sorts of implications for how to stop toxic behavior in an online community. It’s not enough to just ban the jerks; good people have bad days too. Instead you have to teach the whole community what the community standards are. And quickly identify people who are having a bad day, intervene before their toxicity infects too many other people. I think it's a hopeful finding; if you can just remind people of their better nature, you can prevent a lot of bad behavior.