I think you hit the nail on the head with an earlier comment. " The buyer is always right " on ebay. Ebay's policies are heavily weighted to keeping buyers happy, often at the expense of sellers. Selling used items which are subjective as far as condition etc. goes is always going to be tricky.

If we sell those types of items, we need to accept we are going to lose out from time to time and factor that into the profit margin of every item. If there is not enough meat on the bone to cover a few losses, the product line may simply not be viable on ebay long term. It helps if you can adopt an easy come, easy go attitude as getting upset every time something goes wrong can make selling on ebay an unpleasant experience.

I try to factor all of this into pricing and postage costs, run on very high profit margins ( minimum 500% ) and usually just cop it sweet and move on when things go wrong. ( unless a buyer is blatently trying to steal or lie. )