Any dog can be trained, I have had several, some breeds are easier to train than others and within a breed some dogs are more tractable than others. Brutus my Amstaff was relatively easy, we kept him outside so housetraining was never an issue, he would always come and I had him leash trained to walk without pulling in a couple of days. He wasn't around a lot of other dogs or people other than family much so in a way he was never put to the acid test but I never had any aggression issues with him. I despise BSL that targets pitbull type dogs, its a big bunch of bullshit. Blame the owners not the dog. When it comes to training I was spoiled by my first dog, a cocker spaniel, we also named Ace. I don't recall him ever being formally trained but he was a quick learner and would always, and I mean always come when you called him and he was put to the acid test many times, was around lots of people and dogs when I was growing up and we never had an issue with him. To me the recall command, that a dog will come when called is the most important aspect of obedience and having a well mannered dog. If a dog won't come when you call, no matter what else they may do on command, it's not a well trained dog. Ace the cocker spaniel would always come, when there were other dogs around, strange dogs and strange people even when a female was in heat and other dogs followed her around vying for attention, I could always get Ace to come and stay with me when I called.