You have to understand that "not seeing anything someone is doing that is wrong" is purely subjective and based on one's own level of experience and education in the field. I'm an educator, my masters is in teaching and I'm currently working in educational research that has me "in the field" in schools and classrooms all the time. What I see when I go and observe a teacher teaching is going to be very different than what someone who has no background in teaching or education sees. I've seen some really great teaching and I've seen some pretty rotten teaching. The rotten teaching I've seen, the biggest problem with it is that so much of the time when we're working with children, our first instinct in a given situation is the absolutely wrong thing to do. For instance, when your students are being loud and disruptive, our instinct is to yell, right? Well, that doesn't really work. It may work the first couple times as you startle your students (much like shaking a can of pennies at a puppy), but once your students get acclimated to you being the "yelly teacher" they stop paying attention again. The thing to do is actually to lower your voice, or stop talking completely. Wait them out. It works, I've used this technique many times, and instead of adding more noise to a noisy classroom, you're doing the opposite. To the outside observer, the teacher who is yelling appears to be "doing something" and getting their kid's attention (especially if it's still the beginning of the year and the kids are still startled and haven't yet learned that you yelling is a frequent, boring occurance they can just ignore) and beign a "good teacher" while the teacher allowing her students to be noisy and speaking even more quietly or not saying anyting at all seems to be a "bad teacher'.
Cesar Millan has no formal background in animal behavior. He works on gut and on instinct and like in my analogy he frequently does things that "seem right" to the similarily uneducated observer, they seem to make sense. But something that seems right when you don't really know much about the topic can in fact be the last thing that someone who was really knowledgable about it would do. What's especially insidious about his show is the running commentary voiceover and narration that goes on that tells you, the viewer, what to see. But is that really what is actually occuring? Are you being sold a bill of goods in order to sell some books and some ad time? Are you being told how to think by this guy?
