I don't have a solution, but that reminds me of a funny story. When I first got Bandit, I wanted to give him a bath. He is mostly black and white, but he has a little brown on him too - mostly on his armpits and haunches. Anyways, he had gotten a little poopy (you know how puppies are) and there were two little spots on his front legs that I couldn't wash off. I tried scrubbing and scrubbing, but nothing would get rid of those stains. Only later did I realize they were part of his coloring, and not stains!