I just posted one such thread - asking for references for a new hosting company. I've checked my control panel and email and I don't see any kind of details about why it was deleted. Just so we're clear - I'm not asking why it was deleted or causing a stink about it - so this thread shouldn't be deleted... I think (see below).
I went over the rules again and the only thing I could find that could relate was the rule against posting affiliate links. In my thread I mentioned that I'd accept affiliate referrals. Now, the rules don't state that you can't solicit affiliate links - so if this was the reason it was deleted then it seems to be a bit of overkill. Why not edit my post, post that I need to edit the thread verbiage or at the max; close it with a comment.
Now, I understand moderating a forum is a pain in the ass - but it'd be great if there was less ambiguity. I have enough things to do with my time, and speculating about the clarity of rules at a forum I contribute to is a recipe for tedium.