Was the item really not as described? If it was, and the buyer just masses around with you, I'll tell you what my friend did when he has a case like this, (he was very mad on the buyer.....) when he received back the item, he took a hammer and smashed it..... then he took pictures and went to the PD to make a police report, he faxed in all the pictured and EVIDENCE to eBay opening a case that the buyer sent him back the item defective.... to make a long story short he won the case, eBay refunded him all the money, removed the typically bad feedback from the buyer, and sent a private email to the buyer "NEXT TIME MASS AROUND WITH SOMEONE ELSE"
Very stupid to send the email if he filed a false police report ect.
Either way - as a seller its fair to the buyer to offer a return policy.
In most cases, item not as describes is for used items, often the buyer is hoping it is in better condition that what it described to be in.
I sold thousands of items on eBay, and I could count the amount of returns I had.