Sometimes I wonder if programmers should go to conventions not so they can learn new technical skills, but new people skills. I strongly suspect that people will be less inclined to be obnoxious online to someone they can put a face to rather some anonymous entity inadvertently taunting them from afar.
Regarding those who can be obnoxious, I include myself. I try very hard to be civil and I know people appreciate it but I know that I can sometimes let emotions get the best of me. I feel bad when this happens.