We have Winn MH, the style with decals (not full body paint - I wish...) No matter what I try to use to clean I can't get grey grunge to clean away from white fiberglass areas, it's like it is unde...
Mold and mildew can grow INTO the pores of the fiberglass if left there too long.
Try a little spot with about a 20 percent bleach solution; that is, 4 parts of water to 1 part of bleach. If that won't touch it......you are pretty much screwed and paint is about the only good option. Other than just living with it.