back in high school a friend of mine had an overweight cat that whenever you would pet him at the base of the tail, where it meets the body, he would clean his front legs constantly until I stopped petting him there. Well, a few months ago we took in a stray with the same issue, only it's worse. this one is a neutered male and his sensitive area starts half way down his back. if he is touched near the base of his tail, he wips his head around (almost violently) to clean the area. sometimes he will clean his legs and other times he will try and scratch or bite, but he never runs away which leads me to think it's not painful. is this a problem or is it just a feline characteristic of some cats? thanks for any help.