Rudeofus. What would it look like, what should I look for?
There are methods for getting rid of MnO2 stain, while Ag2S is almost impossible to remove. Tiny Silver crystals can be bleached away with C41/E6 bleach (which won't touch Ag2S). This would give you some indication what kind of stain you got. Needless to state that you only need to check for MnO2 right after the bleach step.
Trying to be the best of whatever I am, even if what I am is no good.