I have been restoring cars for 30 years and it changes all the time with the paint products, but rule of thumb is if your nail catches the scratch it cannot be polished out its too deep. Polishing the car multiple times yes does take off material but it depends what type of pad he is using, wool foam, etc. If you are going to repaint the car of course all the prep, washing, prep-sol etc, I would block the car with 600, 800 wet sand paper try not to cut through the clear, address the scratches and reprime those areas with a good 2k primer ( I use Glasurit products in my shop ) block out thse areas spray some color and then clear, you have such a good foundation with the material on the car and after blocking and new paint your car will be laser straight. As far as the swirl marks I am the owner and one thing I enjoy doing is wet sanding and polishing, if you do not know how to polish it will look like sh*t, I know people will comment on this but my painter lays it out like glass, after I bake it for an hour we let it sit for a day or so then I start blocking with 800, 1000, 1200, 1500 and believe me its straight and flat !!! I start with a wool cutting pad and 3M compound just a quick cut, then a 3M white foam with 3M compound, green foam pad with compound and then a black foam pad with 3M finesse and then finish with a good hand glaze, most of the finish glazes I use are Griots Garage I feel they are the best. The reason for swirl marks are the polisher is held at too much of an angle leting the edge build-up with heat, you do not want to be flat just a slight angle for air circulation and I throw a sprinkle of water while I am polishing, never clean-up all the compound or glaze with the machine always wipe off the residue with a soft cloth and never polish from one product onto the other always start with a clean surface and clean the sling off the next panel before polishing. Paint and finish prep is what we are tops above the rest, 2 cars at Peeble Beach 100 points each as well as untold Best Paint at Concours Shows and National Shows. Good luck I hope the easier way works out !
