ARHHHHHHHGHHH! Save me from the alpha boot camp theory! If you want something short and sweet there is an online articel in the huffington post by a veterinarian and animal behaviourist (google dominace and dog training and it should come up), if not I can find the link and post it.
We have freinds who got a puppy while working through fertility issues, neither of them were dog people. They pick a mixed breed (Australian shepherd, Blue heeler, parsons russel) based on cuteness. BAD idea. Then whenshe started to behave like the breeds that she contained they went with a private trainer who suggested a dominace based approach. Long stiry short, lots of rolling her on her back, seemed to work for a while, then surprise, surprise, she started to get really mouthy and her "bad" behaviour returned. They are trying to rehome her at this point and have already had one couple return her. You are welcome to tell that story to your friend, but I think that the articel I suggested has some good opening points about dominace training increasing the chance of biting and aggression.