Not sure what your definition of a dirty light would be. Are you using the light alot in a garage getting grease or something on it? Are you dropping it in the mud? I always use holsters on my belt to help keep clean as possible. I am not sure what you mean rub place on the inside. I wouldn't worry about it if it does not affect the beam quality. If it does bother you to much you can disassemble the head. Personally I would have to clean it out.