I'm just a noob here, but I've been an active member on other vbulletin forums. The one thing that I noticed that made the place a better environment was making the "create a thread" option a priveledge and not a right. In order to actually create a thread on my other forum you had to have ~15 "useful" posts. This caused new members to learn to use the search fuction for common questions, and it detered spammers from making accounts to start malicious threads. This still wasn't an end-all-be-all fix, but it was a deterent, sort of like locking your board up with one of those flimsy dakine retractables.