>It should cause a reasonable person to conclude that the tool doesn't work and should not be used.

But it is likely to cause an FBI-drone to conclude that you are attempting to beat the polygraph and therefore untrustworthy.

Yes, what a strange situation. I lie to prove that the machine can't tell that I'm lying and am branded a liar for revealing the truth.

Maybe the machine isn't meant to do anything, and it's the examiner judging whether you are lying based on how your react to its presence.

The people who run these tests for a living probably have techniques to explain their way around stuff like that. They might say it just shows the subject was deceptive about the whole test.