The paint on the bumper covers is maintained exactly like the paint on the rest of the vehicle. The cautions about bumper cover finishes relates to the method in which finish is applied. Since the bumper covers are flexible, any primers, sealers, color coats, and clear coats need to be flexible as well. Be aware that if you plan on sanding a light scratch out of any clearcoat the definition of "fine" sandpaper is something in the range of 1500, 1800, 2000, 2500, 3000. Any coarser than 1500 as a final sanding will result in sand scratch too coarse for a buffer to smooth out.