Seen it many times. When I hosted tournaments i would get inquiries. People who did not know us were reluctant to participate since they had no idea if we had our heads screwed on straight . (Safe, fair, etc. ) So, I told them to come watch, and if they liked watch as my guest. If they liked what they saw they could participate the following year. Thinking I did not see them, I would follow up with a call. The answer was "My master would not let me watch." I wanted to yell at them "This is America". But I just said O.K. Same with some open seminars I hosted. A few came anyway secretly disobeying their instructors wishes.