I'm quite new on e-bay, but just recently I have had the unfortunate experience of selling a camera to a person who is now trying to send it back as a damaged order. She insisted that it was dented and to cut a long story short no way was it, and she even admitted that she had dropped her husband's camera and had bought mine as an exact replacement. Anyway I decided that I wasn't going to be had by that scam again so here's what I decided to do:
I now take the serial no. of every item i can
I also put that serial no. on the invoice that I send with the purchase so that there can be no arguement about it later on.
I hope this can be of help to some people, as it's a shame that a few people can try to take a livelihood away from the vast majority of honest folk.
Thanks for reading this, and if you have any other ideas about stopping these sort of things i'd love to hear abut them.