Cats have the reputation to be very clean.
They wash themselves when :
- they are wet
- they just passe their time
- they are bored
- they are confronted with a problem
- they fake not to listen but listen
- they have done something bad and only look with one half closed eye to their excited owner
- they are observing guests
But when they are really dirty they don't care !
I could see it when Arthur came back from his mechanical work under the cars and he didn't pay attention at all to the black greasy spots on his white fur.
when Kim had been in the fields and is full of mud
when Lisa, no ! about Lisa there is nothing to say she IS a clean cat.
So I suggest "Wash up, you are dirty !" But of course nobody listens to me and I have to take a damp cloth and do the washing myself. It's mostly appreciated and followed by own washing. (in order to clean my cleaning off ).