Swear filters by nature are very tempermental, and non-"swear" words often fall victim due to the fact that they have a swear word in them somewhere. I've been at one forum where "assume" was partially censored.
I think there should be at least a very lax filter, I'm also liking the idea of optional filtering. This isn't Digg or Youtube though, the kinds of idiots that often plague those places (and fill page after page with useless swearing) don't have a survivable habitat here. We are on a higher discussion/debate level than that, and know when to control our language enough to use swears in the most extreme circumstances for the most part.