Paint on rubber seals and gaskets, ect. What I do is soak good with lacquer thinner and scrape with a finger/fingernail. You may also be able to find something to scrape with as long as it don't gouge up the rubber. Don't use lacquer thinner it if by some chance its an unactivated paint on the part you actually do want to have paint. It may take a little solvent and scraping, but old tape or paint should come off of rubber, You may want to use rubber gloves unless if you don't like lacquer thinner on your hands(and into your body) or you are sensitive to it.
