I don't know that it's necessarily bad or harmful to them to bathe them. It's simply that they're largely self-cleaning animals. But when they have long fur and make bathroom messes, I'm not sure that you have much choice. I've washed cats before, and it's not easy. (The two I've bathed had all their claws.) Just make sure you're using pet shampoo that's appropriate for cats. They have delicate skin that's very sensitive to chemicals, and they absorb a lot more through their skin than dogs or people do. We used to have a neighbor lady who had a long-haired Persian cat who sometimes made messes on himself when he went to the bathroom. She got these pet wipes at the pet store so she could simply clean his rear end area and let him take care of the rest. She also found that keeping his fur trimmed shorter back there was helpful. Also, if the cat is making poop-related messes, something may be wrong with what he's eating. When they're eating a proper diet, their stool ought to be compact and solid and come out cleanly. Make sure your cat is eating fairly high-quality pet food and not drinking cow's milk or cream, which can give them diarrhea.