use a black light and invisible pen when selling

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