You really want to get better at weeding out idiots? Track their IP or mac address and block them based on that. This way if mr. Basher/Pumper wants to be an idiot he'll have to go to his buddy's or the public library to make his posts. They can't even use a different login name because it won't matter.
There should be a voting system going into the negatives as well. After a person starts to take a downturn and show their true colours they can start losing privileges and eventually will only be able to use emoticons to make his/her post. They get the thumbs up or down emoticon for other posts and thats all they can contribute haha. No seriously, other than the emoticon thing I think those ideas would be a good addition.
Gamblor.