Is there any law that says you must keep your license plate clean? I drive a diesel and it produces enough soot over a couple months to significantly darken the back of the car. Is there any chance of being pulled over for more than a "fix-it" ticket for washing the rest of the car but leaving the plate unwashed? I'm pretty sure keeping it as dirty as possible has saved me from at least 1 red light camera. I actually see a SUV/Jeep or 2 regularly that go mudding and leave all the caked on mud on the back.