im a big fan of oppai toys, but one of the problems ive encountered with them is how some kind of black stuff (looks like its maybe hair or something?) always starts to collect around the sides of the nipple, which ends up ruining the look and making the thing worthless. attempting to wash it off does nothing. does anyone know what causes this and how to prevent it? or how to possibly undo it? any help is appreciated as i have lost many good oppais to this