One of my dogs loves them, the other is not interested. I can kinda see why they don't bother cos it's just chewing and they don't really get anything out of them. They can't exactly eat them.
We have had chocolate and vanilla flavoured ones but they were not actually nylabones but an equivalent. I must admit before giving it to my dog i did give it a lick and it tastes of nothing to me, just smells sweet (does that make me strange?!?)