I was on a jury for some guy who murdered his wife...he passed a lie detector test. Of course that was never allowed in court, but after we had convicted him, we read about it in the paper.
I've already seen a poster on FR say polygraphs don't work on people from some cultures because lies don't cause them any stress. It was clear he meant Arabs/Muslims.
Passing a polygraph wouldn't change the minds of 10 people.