My kitty Scooter absolutly hates having his belly touched at all. He sleeps on his back with his belly fully exposed, it looks so inviting, but he will bite if you touch it.
My other guy Clyde will tolerate a few rubs but that is it.
I had a cat growing up, Oopee, who LOVED it. She would see someone coming, and she would flop over and block your way until you rubbed her stomach.