I agree with frobozz (Duncan) and LyleB, the camera you know is better than the camera you don't know. I purchased many of my cameras/lens new and no how much or little they have been used. Don't know on anything I buy used.
In this case, if the body looks well taken care of, it probably is not worn out, just needs cleaning and fresh lube. Dings, dents, scratches, worn leather or brassing, may have a lot of life left, then maybe not. They most likely would need a clean and lube and may have worn out parts.
To each their own.