Do you ever need to wash your cat if you use grooming sprays?

I only had one cat that was so terrified of water he could only be washed with the waterless shampoos. Too much shampooing can cause problems - how often are you combing the cat? I would not use even the waterless shampoos more then a few times a year.

And if the shampoo is made by Hartz or Sargents, then its toxic and should not even be used.

Nope. To be honest with you, the sprays aren't even all that necessary seeing as he's an indoor cat. If he's biting himself then he could have fleas or something similar. Just treat him with some spot on flea treatment to make sure. Brush him daily with a brush which is specially for removing hair so that he's less itchy and won't get hairballs, and use a flea comb daily too which not only removes any fleas which remain, but help get rid of dirt too :)

I have never bathed any of my cats with water or with grooming sprays, and they have really lovely shiny clean fur, and my long haired cats hair has never been dirty or matted and is all soft and fluffy. All of them are outdoor cats too. (I live in the UK so that's the norm) Cats are good at keeping themselves clean until they get really old when you might need to help them more.

Hope this helped!