You also can't leave bad reviews if you return an item.
I bought an item that had issues, wanted to return it and the seller accused me of sending back in a different item. Once I got ebay involved I got them to approve the return, but like a day later I got a message from the seller that I assume he meant to send to someone else accusing them of trying to scam them as well. I almost wanted to eat the $40 so I could leave the bad review, but I know ebay would just remove it or something.