See quite a few doing it but.....The dust and dirt there is transferred to the cloth etc and it leaves lots and lots of spider webbing and some not so small.
scratches.
May not be able to see them close up in right light or the first two or three times. If it was painted black rest assured people would scream.
Good rinse and wash and rinsing pad or cloth between loading with soap solution helps to keep spider webbing and bigger scratching away. Campground allow it if you let their service providers of choice wash it for big sums many times.