I've had pretty good luck selling a couple of guys claimed damage and wanted a partial refund. After granting the first request, I decided to simply insist they ship it back for a refund. I've never gotten any either of the remaining items back, and I'm fairly sure it was just a buyer trying to make a quick buck off me.
I'm not ashamed to say, I'm a pretty good packer, and normally when I ship something, it doesn't get damaged in transit. I can't say that for stuff I've received, I get all sorts of interesting stuff out of the box. 
FWIW, for expensive items, I do put ID on them. If you look closely at any expensive board or inside the shell of a locomotive, you'll find an engraved mark from items I ship. 
