Standard Practice, based on what would happen in a Paypal/eBay dispute, is that the buyer pays for return shipping. The buyer is also advised to use Delivery Confirmation, in cas a Dispute does become necessary.
However, in an amicable discussion of problems, the seller may pay the return shipping. Usually this is because the problem was caused by the seller. This would be a Best Practice.
For example, the buyer recieves a red sweater as ordered, but it is scarlet rather than the cherry he expected. Return would be for Buyer Remorse, and the buyer pays for the return.
But if the seller sent a blue sweater instead of a red one, the seller should pay for the return because he caused the problem.
There is no way of forcing the seller to pay return postage.
Some sellers will accept pictures of damaged items instead of a physical return. This can be a amicable resolution.
