I give my cats flea baths once a month and they have no real issue with it. I've done it since they were kittens and they occasionally will let out a distressed meow but that's about it.

Most of them keep clean on their own all except my Shadow. He is a black longhaired Maine Coon and he is terrible about grooming himself. He isn't fat, infact he's rather thin right now, and he does a terrible job of cleaning his hind quarters. I trim the fur occasionally, cut out mats, and will 'wash' him if he stinks..aka, into the tub you go or a wipe with a wet washcloth. Ah yes, I've wiped more kitty butts than human babies.

He was found as a newborn, eyes still closed, and cord still attached. I bottlefed him, had to bathe him (no other cats at the time) and rubbed his belly to help him 'go'. Lol. My baby. I even had to burp him after bottle feedings. I still put him upto my shoulder and pat him sometimes...just habit. And he usually purrs and likes that position...

Oh yeah, some cats just don't do a good job whether they're too fat or never learned. A good groomer can make a world of difference.