Hi, I live in the city and as you know my rear bumper has taken quite a beating. I know the easiest way would be to replace it, but you know it is going to get all messed up very quickly. Is there some kind of paint that can be used to cover it up? I assume you would need some type of special polymer adhesive for the bumper cuz its plastic? what should i do

Had the same problem in NYC when I lived there.
worst culprits were the parking attendants in the garages there!! Just get some touch-up paint at a local Audi dealer...otherwise spend the $300-400 to get it repainted...
ART.