Familiar Ground

Am I the only one who wonders how dirty a cat will get before that cat refuses to groom itself?  Blood probably won’t do it.  Mud?

Edit:  Just met a friend today and today’s strip was brought up.  Apparently a cat’s grooming habits are genetically ingrained into the breed!  So I guess all cats of a certain breed will groom in a certain way, while others will not groom certain spots on their bodies, etc.  Cats are strange.