This is my old Prowler. It's parked next to the house and there are a lot of trees surrounding it.
I didn't cover it the first 2 years I owned it and I would end up having to wash it in the middle of winter and try to keep the roof clean.. Not fun...
After getting the cover, it would be as clean as it was when I covered it in the Fall.
I was able to trade in that Prowler for the Rockwood when it was about 16 years old and I got more than I ever thought I'd get for it! More than I thought I could get selling it on my own too!
Anyway, I say it depends on where you park it and what conditions it's going to be under.
Mitch