Craig,
Even if you wanted to add the idea of "assuming you'd be getting back the snakes as you shipped them," you still need to say in writing that you would be willing to refund Evan's money upon receipt of the animals. That way, if you feel the need, you could insure that you are not going to get animals back that have been mistreated in someway and then be expected to refund money.
As it stands now, you sold this guy some animals based, in part, on them being feeders. They are not eating, and, in the opinion of the buyer, look as though they never have. OK, everyone makes mistakes; it's cool. However, you have to back up your animals or your reputation will absolutely suffer untold damage. I'm sure you know this, because you've obviously been around long enough to see what people go through when they don't take care of their customers as they should.
Why be such a hard case with this? If the guy sends back your snakes in the condition in which he got them (not including whatever effects they've suffered for refusing to eat for the time he's had them), you SHOULD send back EVERY DIME he sent you! Just tell him that this is what you intend to do, and Evan will undoubtedly ship those critters back to ASAP. Then, you can get them eating again for you, and just sell them to the next person. Don't burn any more bridges than you already have, Craig.
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