> So either 50% of FBI Applicants were actually foreign agents AND believed in polygraphs (why would they if they were trained foreign agents?) OR it's just total bullshit. I think the "it works if you believe in it and some people do" myth is just that...

It's even dumber than that. From what I've heard, the big failure rate is often with respect to drugs. You're allowed to have experimented with marijuana a specific, small number of times.