The gf has a Sheperd mix pup. When we met he was about 3 months old, not house trained and didn't listen very well.
For me, it's rare to have a 3 month old pup that isn't house broke, aside from true accidents which are your fault for not listening to the dog.
Within 2 weeks of our relationship, I had the dog house trained. Basically because I paid attention to him, and he realised he could let me know when he had to go and I would let him outside... She however somewhat ignores when he is telling her and so when I'm gone he occasionally has a mess... But it's her that creates that issue.
I'm the "dominant" one. I am alpha and that dog knows it. She sees a huge change in his attitude from when I am there and when I am gone. When I am there he is quiet, listens and obedient. He still has the puppy stage in him where he gets distracted, but we're working on that.
The big difference is my body language and vocal tone. He knows I mean business, and any attempt of his to be dominant in ANY way gets shot down. That means no cuddling on the couch too. If we have buddy time it's on the floor.
While scolding him (grasping his muzzle, him laying down and my face right in his looking in his eyes) he has tried to nip me once, and only once as he didn't like what he got. Dog knows I'm #1 and that's how it is.
The dog goes nuts when I show up and haven't been around for a few days. Just looses his mind that I'm home, in a good way. Because I'm his boss, and he is a pack animal that's just the way they are.
He is a smart pooch, so when he doesn't listen it's an attitude not an intelligence thing... I do know some dogs that are just plain out dumb, but I think that has lots to do with how they were trained as pups.
I've trained a lot of Labs for bird hunting, positive re-inforcment is the way to go. My Chocolate lab is great, I've almost never had to scold him, he just wants to please me... But for some people, he could care less to listen.