I've had 2 negatives in over 10 years. One was due to USPS taking their time shipping the item and the buyer negatived me, then got the item a couple of days later. The other was after I gave a full refund including shipping and told them to keep the (now) broken part, that got damaged in shipping.
That's terrible! Ebay should have a way to protect sellers who give full refunds.
I'm learning that Ebay BUYERS are total idiots. I just sold an AD electric wiper motor conversion unit. The buyer started a return because he "thought he was buying wiper blades." WTF - how do you confuse a motor with blades??? On another part, I posted two photos with a tape measure beside the part to show its dimensions. Despite that, THREE people messaged me asking how long it is. WTH???