You really can't. When dealing with high priced items, always ship with insurance and signature confirmation. It costs more but it's worth the trouble. I'd had

You really can't. When dealing with high priced items, always ship with insurance and signature confirmation. It costs more but it's worth the trouble. I'd had cases where the seller claimed the box to be empty. I've had cases where they claimed it to be damaged. Whether they are lying or not I don't know, but that's where the shipping insurance covers it. The cases that the seller does want a return, you really can't say no. I usually just say yes, I can process a return, but can you explain what is wrong with the item? Maybe we can walk through it before processing a full return. Usually you can get away with compensating them something since no one wants to go through the hassle of the return. I also make sure I tell them to ship with signature confirmation and tracking. Since I offer "free shipping", that means they would have to eat all the costs when they return the item. More often than not, it's not worth the hassle for them. After hundreds of sales, I would say there are definitely some complications, but more often than not it's fine. It's one of the risks you have to consider when selling.