I've been on forums in the past where there's a definite "clique" and if you're not part of it, you're seen as an outsider. I've been on others where people have spats and fights with others for: having a different opinion to the general consensus, not using correct SPAG (or correcting others on it), posting daily news items (whether it's related or not to the forum theme), lack of experience, or even having professional experience (because you're then giving an opinion that others don't like), and of course the usual religion/politics stuff.
You tend to learn which forums to join and which to avoid/leave. This is one of the better forums. I suspect car forums will tend to attract more people from a wider cross section of society so you'll get more people coming up with very opinionated/uninformed posts, compared to say a very specialist forum eg torches.