I was thinking of more of an interactive training system that users have to pass through to activate their account. It would ask a lot of questions like:
(Screenshot of an old forum post followed by a year-late reply)
How do you feel about the replier to the post?
A. Nothing.
B. The poster didn't make a relevant post.
C. The poster shouldn't have replied to an old thread.
With option C. taking the user to the following:
Why?
(textarea for user to type a response)
At the end of the exam, if the person has a lot of questionable habits, we force them to go through a 4-page introduction to our forums, and then give them the option to submit their application for review if they want to join. Then their application would be posted as a poll to a sub-forum where we could collect input from existing members based on the open-ended replies they chose to give.
Then only those who can obtain a referral from members of the "Invite" group on the boards can skip the process.
Of course, we'd never really do all of this, because then the forums wouldn't be open to everyone...