use the invisible pen and mark items you sell. there are people out there that will buy your digital camera and then email you saying it doesnt work. you're a nice seller so you take it back but they mailed you their broken camera. you've been had. you can prevent all this by telling the person that wants a return that they can mail it back and that you will scan it for a special marking you made with an invisible pen. this will deter them and they will try to get over on someone else. it costs about $10 for both and is well worth it!!! key words camera clothes electronics collectibles