I'm a member of quite a few. One is an all dog breed general forum. I never really noticed that except perhaps they would have a debate about clothes or something. Don't really remember. I'll have to look at siggys next time. Come to think of it they are definitely far from friendly to each other in certain sections there. I just found most of the community to be unwelcoming. I go there occasionally, but it's not worth my time or energy. I put that into YT.
I am a member of a disease specific animal forum and I'd have to say they are amazing people and I never see arguing either! Their site rules are about respecting others and such. I don't need to go there often, but I really like how the members act toward each other and newbies.