I have fairly sensitive nipples and I love when a lady gently nibbles and licks them and i diffidently enjoy returning the favour by gently sucking,licking and nibbling the ladies nipples. But i think the reason some might not be as sensitive as others can be down to the technique used.I think nipple play is like licking pussy or ass or how a guy likes his cock sucked everyone likes it done differently. It's just a case of finding out how each one likes it done. And that can be a lot of fun.