I tend towards this camp as well. I'd ask a couple of questions, like what tool they used and ask for a close up of the cup, like DD suggests.

You might ask for a slight reduction in price, since you are taking a risk. How the seller responds to this will tell you something about what is going on here. Over response would indicate to me the frame is okay. If they're willing to lower the price, it may be a real issue. But this is purest guesswork.