I love the complexity of English that this billboard
indicates. I’m glad this is my native
language and I was raised with it, otherwise I would read this billboard as announcing that their product is a dirty fighter who breaks the rules. Or I might think it was a mistaken spelling
that should read “We fight dirt.”
However, while we don’t speak it this way, English is so flexible that we know the billboard is saying: their product thwarts dirty engines. An adverb/adjective has been used as a objective noun.
The Japanese make jokes like this all the time.