Years ago, while working at a camera store, we received a pristine Nikon F2 body in trade. The problem was, the previous owner had engraved (scratched) his SSN in two places on the camera body. It seems that, back then, the police departments were encouraging this practice in order to reunite owners with their property if it had previously been stolen. The shop owner was convinced that no one would ever buy it in that condition, so he let me have it for a very small price. To this day I still own it and it works great. I don't concern myself with the engravings and can only assume that if it were ever stolen, whoever the person is with the SSN on it would end up getting it back.