It's said to be fairly easy for an intelligent person to fool a lie detector. I haven't studied the matter, but I would imagine it would be largely a matter of practice, of repeating a sensitive question to yourself until its shock value was defused, and of meditating on something calming, like imagining yourself lying on a green hill in the shade by a lake, or that sort of thing. Same thing you might do to control pain at the dentist.
Would this work? I don't know, but I suspect it would.
In the proper setting with a good operator, and the right questions, etc. etc., a "lie detector" is going to provide some interesting info. Where it might not be of benefit is testing lie detector operators or experienced individuals. Some people are much better at lying than others.
I know a tack in the shoe screws it up. That's why they make you take off your shoes during testing.
Or someone whose been taught how to fool it. I've heard that puckering your hindmost orifice is one trick.