I co-own a pretty large forum dedicated to progressive music:
http://www.progressiveears.org ... I've been on it for 11 years - and decided from the get-go to "play nice".
Lucky - because I've since met several hundred of the forum members face-to-face, and have become "real-world" friends with many of them. (In fact - just on Wed. night, on a business trip to Boston, I met 2 forum members for the first time.)
So it's definitely worth being decent on the forums, because if you hang out here long enough you will
probably end up meeting - or riding with - many of your virtual friends.
On the other hand - we had a member (one of several who we had to ban) who was an unbelievable troll. He pitched up at a rock festival one year thinking that no one would know who he was. He was friendly and came across as "mister-nice-guy". Then - someone figured out who he was and called him out, and the guy was so embarrassed that he left the event a day early.