All buyers have 100% positive feedback, as negative feedback can only be left for sellers. So you can't really make anything out of the fact that someone has 100% positive feedback as a buyer.
It's still possible they could pay. Sometimes, the buyer isn't aware there is a problem. People don't always check their email, but they'll usually notice if they log in to eBay and there's a claim against them.
COMC auto accept is currently set at 35% off.