I've had both experiences - I was put off by others' reactions to my postings a couple of times, and I'm sure I have been guilty of what you might call 'inappropriate spontaneous reactions' myself. So I think Wolfgang's suggestions are a good way of keeping that kind of off-putting postings to a minimum.
I don't mind the fun and the tangents, though. Along with the learning, they make the Mudcat what it is. I've recently started to follow a few newsgroups, and compared with the shallowness, the flaming and the lack of charity towards each other I've encountered there, Mudcat is Paradise!
So I was never tempted to leave, although I may choose to keep quiet on a lot of topics, either because I don't believe I know enough about them or because I tend to avoid (to me) pointless controversy. (I can't say I was too sad, though, to be on holiday just as the Mudcat was going through a fairly sticky phase, and I'm happy to find we've got over it, have been extremely nice to each other for a while, and that Bruce, Martin and now BAZ are all back on board.) - Susanne