I think I created a topic about this in the past, but couldn't find it. I think the product I was recommend was REMOVE-ZIT, but I am not sure.
My RC Batman has the blue stains on his face. My Batgirl has red stains on her face from her hair and I got a couple of old GI Joe's that have that odd gray/blue staining on their faces.
Would REMOVE-ZIT take care of them?