I imagine it would leave holes and the paintwork even IF originally the same colour underneath is likely not to be any more - I always fancied fitting some to mine to help protect it when laning.
they do come off but they leave holes in the doors.have got a set to fit to mine when the weather gets a bit better.
as terranosaurus says a bit of extra protection when out laning.
They are good for stopping the supermarket door bangers you get, you know the ones that forget how close they parked and force open the door on to your panel work