It isn’t going to “catch” everyone but it is another way to reveal people with vulnerabilities that could be exploited. I think the real issue is people that “fail” the polygraph, since it isn’t actually a lie detector in any sense. It would be better if they just considered it a polygraph assisted interrogation.
I've done periodic polygraphs, both lifestyle and full-scope, every 5 or so years since 1997. None of mine have ever lasted longer than 30 minutes.
You just sit in a chair while wearing some straps and there's never been any yelling involved.
It's all quite prosaic and relaxing actually.
It has been my experience that the clearance investigation process is quite simple, although I lead a very boring and law-abiding life.
I know of some people who have had quite long polygraphs and failed them repeatedly but my hunch is that the examiner has the findings of the background investigation in-hand and is trying to clarify some findings.
Many people with past financial, drug, or legal problems have gotten through the process with no issues just by being open and honest with the investigators and polygraphers.
So yeah, if the background investigator interviewed a friend of a friend of a friend and was told that 20 years ago you used to get stoned in college and whip your dick out but when asked during the polygraph about past drug use you go "I've been a squeaky clean boy my whole life" you're gonna have issues.
The annual financial disclosure is much more stressful just because of all of the damned paperwork.
1) are you willing to play by the rules and follow orders, even if sometimes they don’t make sense?
2) if you are being lightly interrogated, do you immediately freak out and tell the interrogator everything? Do you have a really bad reaction to pressure?
If you don’t match these criteria then you probably aren’t fit to know extremely sensitive government secrets. But like I said, it’s more of a ritual than anything, the value for even those two tests is unproven.
Even smart and informed people who know exactly what a poly does can say and do things they wouldn’t normally when they’re strapped to a chair, hooked up to machines, and being yelled at for hours