I never preview before I post, although I do proof read in the text box. Since my posts are usually short anyway it's not difficult, and I don't do anything as complicated as html. I also tend to stay away from threads where people argue so I don't worry about offending people. Normally when I delete my post it's because I decide it isn't relevant or interesting, or it isn't as funny as it was in my head. Mostly it turns out to be not funny. I'm so much wittier in my head than in writing. Forums are places where you actually do have time to think about the perfect comeback, unlike in real time conversations where you have to make do with what you can think of in a few seconds.