When I had my shop I'd offer the service as an "up sell" benefit for my cutomers. While we were fixing the accident damage in the conventional manner I'd have the mobile guy I used come in and do the small dings and such on other parts of the car. This usually only appealed to the higher end owners who had some level of emotional involvement in their vehicle rather than viewing it like just another appliance in their life. I'd have him take out the door dings on my truck periodically (amazing how no matter how much you try to park in places where it shouldn't happen these little dings "magically" appear) Like any other skill based craft not all paintless dent guys were equal, somes better than others.