Excellent link! Deception can work best when you can create and sustain an artificial environment which simply reinforces previously held thoughts and perceptions. Many people are not consciously looking to deceive themselves or others. It is simply an easier task to accept what you want to believe rather than seek to see if your thoughts, beliefs and perceptions can be sustained when actively confronted, challenged and tested.
One of the remarkable benefits of martial arts training is that you are given the opportunity to actively test where you are so you can better see where you would like to go. This process can easily be covertly thwarted when a person remains within their self-defined/confined environments.
I frequently remind myself of something that Ushiro Sensei said: the biggest impediment to your learning is what you think that you know.
The best thing about continuing to move the impediments out of the way of my real learning, has been the ever-growing camaraderie of those I meet on the road to greater discovery.