I think it was Msloke who uses a product called Angel's Glow and has had success. How old is your dog? Could he be teething? Also, you might want to check for an ear infection or ear mites. They can cause excessive staining as well. My dog does tend to get pink paws from the grass. Now that it's a bit colder here, they are definitely fading. During August, they were especially bad.
edited to add...I think he is adorable regardless of the stains. His face looks so sweet!