This is really interesting post - as Ben is a very grumbly dog, and has bitten/nipped me several times. I supose I've just accepted him for the way he is now, I know his limits, I know I would never trust him with kids or if someone pushed him too far he would bite.
However I also know i have to accept responsibility as we made tons of mistakes when he was little. He was our first dog and was always dominant and we have battled on and off with behaviour issues.
I suppose I could get a behaviourist to help with the nipping, but to be honest, we just accept it as part of his personality and avoid potential situations where we are going to clash. I don't allow certain foods that he guards, and he does know we are in charge - its just that he challenges it sometimes, where i suppose other dogs wouldn't.
I think I agree with other that you set your own boundries - we accept more from him that I'm sure more experienced dog owners would allow, and I know we would do some things different with another dog, but we just love him to bits and for 99% he is a cuddly, affectionate boy.
Bens mum