Scott Wade is an artist who "just can't resist a dirty rear window." He creates amazing works of art using dirty cars as his canvas. In short, he goes well beyond writing "Clean Me".
Implications - If Scott ever brought his form of street art to my car, I don't think I'd be upset at all. After all, it's not permanent and might even provide a good incentive for me to get it washed. With that being said, some of his dirty car creations are actually really stunning. If I came across a Mona Lisa painted out of dirt on my window, I might actually end up inclined to never wash it again!