Mine has that too. Its cool and not so cool. Camera gets dirty, but I can spray to clean it. Driving in rain you just see water kicked up from the tires so it's all you see. Its also harder to gauge distance IMO. On the plus side, if you have the back window blocked by heads in the back seat / recently purchased a big object like a TV, it's a great backup so you can see out the back. Also, mine at least seems too use a wide angle camera, this is pretty nice since you can see blind spots and more lanes when on 3+ lane highway.

That seems really rough anywhere with snow. Whole car accumulates so much crap on it that gets kicked up in the winter between freeze/thaw cycles, dirt that gets shoveled/plowed with snow, slushy muck getting kicked up from the road when it's just close enough to freezing to form, etc.