Was cleaning a house today for the first time. As I was cleaning the windows the black rubber around the seals was mixing with the water and dripping onto the window seal. No prob me thought but when went to wipe it it just smudged and looked horrible and then would not come off. The next windows I was more careful but still had a bit. Apart from being there hours with some stuff on a rag cleaning it I must admit I was stumped. Anyone else had this problem and can you stop it. Please help.