I recall reading through the TOS of a seller who had clearly been antagonised one too many times, they were a bit more entertaining (read: tongue in cheek) about it though.

It was a few years ago now, so my memory isn't too crash hot, but there was a long list of reasons a buyer will be blocked (including - ask a stupid question, you'll be blocked etc).

But my favourite bit was about postage.  There was one bit that was along the lines of if I charge $10 for postage, then postage is $10. If I discover you live next door to me, I will bundle your purchase and toss it over the fence, and you will consider it delivered and be grateful for it.

His FB left for buyers was similarly awesome. I do remember this one word for word:

This buyer bought my item.