Buyer's remorse happens, and it not something that is considered a highly valued trait here. In fact, it's a path to people never doing business with you again. We do not need tire kickers here, period. If there is a legitimate issue then the buyer needs to explain and demonstrate what that issue is, and why after seeing pictures it is not acceptable. I agree with Wolfman that if you go refund, you subtract the shipping costs you as a seller incurred (that is if the item was somehow misrepresented). This is why some people only sell to members with high feedback and tenure on forums, they know their chances of success are higher.
So if the deal is undone should the seller post feedback? And in turn, would the buyer be within the rules to also leave feedback?