Am I hurting my cat?

I have a Domestic Shorthair cat that I groom once a day and wash once a month.I wash him with that "dry" brush out shampoo.I use very gentle grooming tools and I groom him as gently as possible but he still squirms and snarls as if I am trying to kill him.I use a rubber mitt to loosen dead hair,a wide toothed grooming comb to extract the dead hairs,a slicker brush (for shorthairs,groomer said it was ok to use) and a natural bristled brush.Am I doing something wrong or is he just bieng overly dramatic? He has never liked to be handled or cuddled.(but he loves to be scratched and stroked =D)