Anonymous,
I think many people who post to this website are reluctant to provide much detail about themselves out of fear of being identified by the agency with which they have applied for employment and suffering retaliation as a consequence.
With regard to the FBI, I can tell you precisely which relevant questions I was asked during my pre-employment polygraph interrogation in 1995. I believe the relevant questions asked today are similar, or perhaps even the same:
Series I
1. Has anyone directed you to seek employment with the FBI?
2. Other than what you told me, have you ever been in contact with anyone from a non-U.S. Intelligence Service?
3. Have you ever provided classified information to any unauthorized individuals?
Series II
1. Have you ever sold any illegal drugs?
2. Have you ever used any illegal drugs?
3. Have you deliberately withheld any important information from your application?
I truthfully answered, "No" in reply to each of the above questions. But my FBI polygrapher reported: "It is the opinion of this examiner that the applicant was deceptive when responding to the listed relevant questions in Series I and Series II."
I "failed" every single question! Like you, I had thought that I would pass because I was telling the truth. It never occurred to me to do any research on polygraphy before my "test," let alone to learn, practice, and employ countermeasures. I was naive.
Instead of getting "freaked out" about what you've read on this website, I suggest that you consider it with a level head. The "Control" Question "Test" format that the FBI and other federal law enforcement agencies use for pre-employment polygraph screening is inherently biased against the truthful, because the more honestly one attempts to answer the "control" questions, and as a consequence feels less stress when answering them, the more likely one is to fail. You'll find this explained (along with the other trickery behind the "test") in Chapter 3 of
The Lie Behind the Lie Detector. About 1 in 5 FBI applicants who make it as far as the polygraph are branded as liars by this fradulent "test." Ultimately, you must decide whether to employ protect yourself against a false positive outcome or not. But I think it is foolhardy not to.