I think these forums are an outlet for most people. We're all basically anonymous and free to talk about things that we've probably never discussed with anyone before.
That freedom can be overwhelming at times, making us say some crazy sh;t. I have rules about posting that I rarely follow; I guess I should call them goals:
1) Never post while drunk. The freedom of anonymity mixed with alcohol removes all inhibitions.
2) Never post when in a foul mood. Misery loves company, and our bad feelings can be easily spread to others.
3) Never post while tired. I've read posts that I'd made in the middle of the night and saw that I left entire words out of sentences.