I had this very same conversation with another person. I was told that some restoration/customizing experts use some kind of marking left behind so if something like this happens it can be traced. Not sure exactly what they use.
I agree though. I don't mind jersey restoration to bring an item back to its original form. However when you are creating or changing a jersey to something different you are opening the door to this kind of stuff. Even if your intentions are good. All it takes is one bad person to do this.