I reckon never. Shit threads die out on their own e.g
(and there is no obligation to read them). If you're offended, tough: don't read it, or leave. The principle behind this forum was freedom of expression, and if everyone chooses to express that someone else is a cunt, then I think that's fair enough. Of course, I do agree that certain edits may be necessary, for example removing anything which is against the (small, reasonable, and necessary) set of rules, or something which violates a persons privacy, but I think that is far enough and that the offending topic should be allowed to continue with that particular piece of content removed.