Leaving negative/bad feedback

Well, here's how "I" see your situation. You bought something. It didn't meet your expectations. (Insert reason here, it really doesn't matter) You sent it back and got a refund. In "MY" eyes, at that point, YOUR business is over with that seller. You were not out anything. Leaving negative feedback because the seller is selling said item to another buyer is a f%$ked up reason. That's none of your business at this point what he does with it. I would have left the guy positive feedback in that situation, because he refunded the money. Quite obviously, if he were trying to rip people off, you'd never have seen one red cent.