Prevent scams or honest mistakes by: 1). Insisting on making note on the paperwork of any scratch no matter how small before you leave and 2.) taking dated photos of the car in the parking lot when you return it. I returned an Enterprise car in Edinburgh at the airport before hours and used the key drop. The next day they called to ask when the car would be returned. Two days later they still had not found the car. I sent them a dated photo showing the car in the lot, with their sign clearly showing and the license plate of the car showing. They sent me a closed out invoice the next day. (I still don't know if they ever found the car.)