I've been using this method on Kira, who's new and very aggressive. I think it's working. She sulks after and really hates it. My mom pointed out that blowing in faces is a sign of dominance for some animals, and so it biting. So, when they bite you, they're saying, "Do what I want, I'm the boss." And by blowing back you're saying, "No, I'm the boss, stop it." Course, it doesn't work on every chin, but I guess you just have to find a way to tell them off!