I know some govvies who have been through the polygraph circus.
One guy knew it was BS and could not get worried enough for them to come up with a baseline - he was too calm. So they took the tack of rescheduling it a bunch of times, making him go home after showing up so he would be good and pissed off when they actually did the test. He passed.
Another lady I know had the interviewer go so hard on her she was crying through half of it. Afterward, the interviewer told her the goal was to make every interviewee break down so they would reveal stuff.
One guy knew it was BS and could not get worried enough for them to come up with a baseline - he was too calm. So they took the tack of rescheduling it a bunch of times, making him go home after showing up so he would be good and pissed off when they actually did the test. He passed.
Another lady I know had the interviewer go so hard on her she was crying through half of it. Afterward, the interviewer told her the goal was to make every interviewee break down so they would reveal stuff.