I talked with an Instructor Examiner about this a few years ago, and he was the person who told me that big IDCs do indeed promise a 100% pass rate, and they do deliver on it. They do that by teaching a specific methodology for teaching each skill, and they drill them over and over and over and over until they have it down perfectly. He said that if you were to line up a set of their candidates and have them all demo the same skill at the same time, it would look like a synchronized swimming routine.
He was not in favor of this, BTW. He said that it leads to the misconception that there is only one acceptable way to teach a skill. The good side of that is that the the IDC we were discussing has since switched its synchronized swimming routine from kneeling to neutrally buoyant.
So here is a question. I am sure everyone agrees that Snow's performance was horrific. Can anyone point to anything she did that indicates she did not do a perfectly fine job at an IDC/IE, or that she could not pass an IE if required to today?