I my line of work, I have to sign my name and provide my certificate number to everything I repair, replace or adjust. It wouldn't be hard to track down anything I do after we send it out of the door. Thats why have another set of eyes look at what I've done, even though I have 55+ years of experience doing what I do. I have the same approach to everything I touch, including my own stuff. A while back I bought a 273 Barracuda off of a young fella, who told me his dad had rebuilt the engine for him and he hadn't got around to putting the engine in the car. He told me his dad was a good mechanic. It hadn't been rebuilt, nor disassembled, it was just cleaned and painted. I didn't have the heart to call him and tell him about it. After all I was just getting the car for spares, it just happened to have come with the engine and transmission.