I'll tell you, I am a member of numerous forums, and SimV is the most relaxed, easy going of them all.  There aren't many trolls looking to start fights, and we all have gotten to know each other pretty well.

The worse one I visit is a firefighting one.  The problem is, most firefighters are aggressive Type A personality people, which is what you want when your house is one fire.  But a discussion in that forum can get nasty quick, especially on controversial topics.