The last two threads I've posted on have been deleted for reasons I don't really understand. One was about the royal family and the other was about infidelity. Neither was (as far as I saw) libellous. The latter was zapped because it (quote) 'wasn't going well'. AFAIK there's nothing in the Talk Guidelines about threads having to 'go well' in order to remain.
I think it would save a lot of time if @mnhq could just confirm that we're banned from discussing certain topics. I'm sick of wasting time on threads which are deleted for the thinnest of reasons.