I remember selling some used textbooks on Amazon back in my student days, and for the ones that needed returning, I remember that having the buyer eat both send and return shipping charges STRONGLY deters frivolous returns.

"In cases where you are not responsible for the return, the return shipping costs should be borne by the buyer. Upon receipt, please issue a refund to the buyer. Learn how to Issue a Refund."

http://www.amazon.com/gp/help/customer/display.html/ref=xm_1...

Seems like the seller could have just asked the guy to send it back (at his own cost) before giving him a PARTIAL refund (book cost sans shipping fees) and just avoided this all. :)