filthy, foul, nasty -- (disgustingly dirty; filled or smeared with offensive matter; "as filthy as a pigsty"; "a foul pond"; "a nasty pigsty of a room")
dirty, filthy, lousy -- (vile; despicable; "a dirty (or lousy) trick"; "a filthy traitor")
cruddy, filthy, foul, nasty, smutty -- (characterized by obscenity; "had a filthy mouth"; "foul language"; "smutty jokes")