Each person has to answer that for herself. IMHO the buyer has a responsibility just as the seller does. And that is to report any shipping damage, cosmetic damage or functional issues not described in the ad in a timely fashion and to aid in the claim with the shipper should that be required.
It is also the buyers responsibility to bring reasonable expectations to the transaction. So, to me, the transaction is not complete until the buyer acknowledges that the item is as described, or is reasonable in coming to a resolution with the seller in the event that it is not, and that may be as simple as packing it securely when returning it.
Then again, I often give a buyer feedback as soon as I receive payment.