I'm currently active on some political forums, some anti-political forums, some geek forums (Linux, FreeBSD), a bunch of still photograhphy forums, the occasional Jeep forum, many listserve groups and a few Usenet groups, some small-format cinematography forums... prolly I am active in 20 or so at any given time. I don't post to all of them daily, of course, since I have a life. I think.
Some forums like political or anti-politcal forums, exist primarily to facilitate heated debate. That's their purpose, so it would be hard to piss them off enough to get them to ban you. They encourage it. It would take some serious effort to get tossed off of a forum that celebrates differences of opinion.
For the rest, especially the focussed hobby forums, I try to stay mostly to topic, saving any contentious posts for the forums that welcome it. That's a good way to avoid running afoul of the rules, and to maintain good neighborly relations with others on the forum..