What is Dirty ?
Dirty is (adj) 1. not clean After the party, someone has to wash all the dirty plates. Don’t come into the kitchen with your dirty boots on. 2. not honest, not done according to the rules He never uses violence himself, he just gets other people to do his dirty work for him. There was some dirty play from the other team. He’s one of the dirtiest players in Football League. 3. pornographic, about sex He keeps the dirty magazines on the top shelf. He makes his money selling dirty postcards to tourists. 4. dirty look an annoyed or disapproving look He got some dirty looks from the traffic wardens. (verb) to make something dirty, or to cover something in dirt Look you’ve dirtied the clean kitchen floor! Synonym soil. Antonym clean (NOTE: dirtier dirtiest)
source: Easier English, Student Dictionary Upper Intermediate Level