He's 'filthy rich'. [=he's extremely rich; he has so much money that his wealth is disgusting or offensive]
He has a 'filthy' mouth. [=he uses language that is very offensive]
He has a 'filthy' temper. [=he gets angry very easily]
(..) to this lady. And if she ever wakes up, we'll do a whole lot more. But one thing we won't do is sneak into her room in the night like a filthy rat and kill her in her sleep. And the reason we won't do that thing is because that thing would lower us. (..)2003 Kill Bill: Vol. 1