Meh, I have been having issues on Amazon used sales lately. Thus far, nothing that ended completely poorly... but,
1) Guy buys phone. Guy finds out phone doesn't work on his network. Phone model was exclusive to Verizon, and the reviews all stated such. Guy wants a refund. Amazon suggests teh proper way to deal with it is to offer a full refund and that it is the cost of doing online business. After some back and forth, the guy is going to sell the phone to recoup his loss... nope, wants a refund... nope, it sold. Nvm.
2) Guy orders my used tablet, the following morning, as I am finishing up the packaging and about ready to pay for and print the label, I see an email pop up that he wants to cancel the order because he that it was the new version of the tablet. I just missed running into the same issue i did with #1. Tablet sold next day, so not a huge deal.
Long story short, there are a good number people that buy things that are idiots. For whatever reason, the sites the offer to allow you to make these transactions tend to suggest that you the seller bend over for the buyer. I do think Amazon isn't as bad as ebay, but I have only sold a few things thus far and only 1 of them went completely without issue.