betterwithcats.net
If your indoor cat is healthy and young, there is actually no need to bathe her at all.
A smelly or hazardous situation
Health issues, such as a bacterial infection, or a ringworm
A cat’s advanced age
Obesity
Tangled Coat
Indoor cats will not need frequent baths, with the exception of hairless cat breeds. These cats have sweaty and oily skin, so, it is necessary to give them a bath once a week to maintain their skin and coats healthy and clean.
If you wash your cat often, this might remove the protective layer of natural oils in her coat. So, provided your kitty is healthy and perfectly capable of grooming herself – you should not wash her at all.