Good post.
At a point in my career I took a number of start up polys and then follow ups every 6 months.
Polys measure anxiety, nothing more. I flunked a few, answering truthfully, then retested successfully.
Modern polys use a -5 to +10 scoring to minimize cheating by sociopaths and drug users. With the best score being a 3. Negatives show deception by being too calm, or someone under the influence.
The greatest variable is the experience and discipline of the examiner. I have asked for a blind 2nd opinion of the results by another examiner and the scoring was sometimes different.
The best examiners are very careful to elevate the base line throughout the test as anxiety tends to increase as a matter of fatigue.
That is critical along with a rest period between questions and limiting the subject matter to a max of three different subjects with several minutes between subject groups.
Ask the examiner if they have ever scored someone as inconclusive. If so, stop the exam and get someone else.
Finally, ask for and get a copy of the poly readout and an audio tape. The examiner may mismark the answer response time window.
If you distrust the competence of the examiner, there is no harm, only benefit to stopping the exam and getting another.
I can beat any polygraph.
FBI and DIA agree.
And I am not a sociopath or psychopath.
I have been trained to control galvanic skin response, and Zen which allows substantial control over heart rate and respiration.
Oddly, it was not government training, but something I picked up at the local community college.