In the UK you could go into an auto parts shop, and ask if they have any powerful degreasers / cleaners that are plastic safe. It removes grease, oil, wax, tar, and dirt. Paint too obviously, but the bottle won\'t tell you that. To help further, it\'s made up of:
Water, 2-butoxethanol, nonyl phenol polyethoxylate, sodium xylene sulfonate, and sodium hydroxide.
I\'m guessing it\'s that last ingredient that does the business?
Oh, and if stripping metals, just go into any hardware store and buy a regular can of industrial stripper. Not plastic safe, but with metal the paint just falls off.