My job requires polygraphs, so I had to get one again. This is only a small portion of what happened. 

They requested that I bring a copy of my Sf86 as well as a list of all foreign contacts, travel and prescription medication.
My Sf86 was most recently submitted electronically. I had a vague notion of seeing if I could find a paper copy of an old one, but I didn't end up bringing it to the first test. They specifically asked me to bring a paper copy of the sf86 to the second exam. That is what made me decide not to even attempt to find it. I thought that if that was something they needed to have then they should be able to retrieve the information themselves. 

I failed twice. My first polygrapher got upset when I used the term failed. They insisted, "I didn't say 'failed'." It became a common refrain for them to state ,"I didn't say that." "I didn't say that." In response to something they stated, I asked "So telling the truth isn't enough?" They replied, "That's not what I said."

I felt like I was being blamed for all kinds of things.They fussed about the clothing I was wearing, my dietary choices, the fact that I brought something to read with me...


For the third exam I said "screw it" to their advice and threw myself into research. Found the polygraph book and practically memorized chapters 3 and 4. 
I saw some advice suggesting not to bite one's tongue since they might see the movement. Well, in the age of facemasks, that's one less thing to worry about.

The third time around, I followed internet advice almost to a T. I chatted with the examiner about football, but clammed up on details about myself. When asked about foreign contacts I said things like "I live in [a diverse part of the country]. I may or may not encounter individuals who may or may not be US citizens. I do not interrogate people on their citizenship or immigration status."
When they gave signs that things were not going my way, let's just say that I paid special attention to the manner that I answered certain questions like: Do you believe I will ask you any questions we have not discussed? Would you ever knowingly decieve anyone close to you?
And wouldn't you know it, the examiner reported that he was getting reactions on the integrity questions.
They tried to come back to the foreign contacts. So I answered,"I use stores and shops on a frequent basis. I may or may not encounter individuals who may or may not be US citizens. I do not ask people about their citizenship."
They kept trying to ask about it and I gave a generic response about having reported everything that needed to be reported.
At that point I figured if my final exam was a failure and I needed to find a new job then there's no point in talking to them further. If I had passed then talking would only make things worse. I actually knew a guy who passed his exam but then felt guilty about something and went back in and talked to them which then caused him to fail.

They had strange ways of administering the test. They variously, put my feet on a stool, switched from adult to child blood pressure cuff. Put the cuff on my biceps, fore-arm, and leg. 
They put the metal finger pieces on, then switched them out for a palm reader (basically what the whole test is) then back to fingers back to palm. At one point I just offhandidly asked if everything was alright or if the machine wasn't getting a reading or something . I later got accused of showing disdain by asking questions about the machine. 

They put a plastic shopping bag over my hand and asked if that was "warmer."
I answered with something noncomittal like "okay." They disparaged every thing that I said or did so I decided to waste as little of my breath on them as possible at that point.

Lessons learned:
Treat them like cops: anything you say can and will be used against you. I came up with a generic answer that I used on the third exam and will use in every exam in the future. It goes like this:

When they ask about specific details about anything at all, I will continue to say:
I have reported everything that is reportable. Anyone who has a need to know that information will be able to access the reports.

Preparation works. I did not reveal something that they would have been VERY interested to know and I got away with it despite questions that addressed the very subject. These machines can't read your mind, the examiners are human, fallible and not omniscient.

So after three tries I finally passed and I shouldn't have to worry about it again for several years. 

Questions, comments, concerns?