1) People ask questions and get slammed in the most condescending way. Bad idea. Never do that. What is wrong with you? All instead of actual discussion and conversation.
2) People come to forums with nothing else in mind but to talk about their projects and post bits of them. Read my stuff! Here's my stuff, lookie lookie! I don't really care about anything else. While passion for one's work is nice, a little give and take is better.
But writer forums can be really useful for learning tips and tricks, finding out where to query and where not query, and just to know you aren't alone in your writing.
And that's all I have to say 'bout that...