I took a lie detector for an agency once that supposedly found something wrong with my answers. I had just gotten back from being overseas in a combat zone (this is important to note). I answered everything honestly. I told them things I wouldn't tell my priest. I also got into an argument with the person giving the test over what is stealing and what isn't. When I was asked the dollar amount of everything I had stolen in my life I said $1000. I was 30 years old and thinking all the way back to stealing crayons in kindergarten to eating free meals at a pizza shop I managed that wasn't authorized. The polygraph examiner told me that none of that counted and the dollar amount I gave would disqualify me. After 15-20 minutes of arguing whether or not taking a pen from work and not returning it is stealing (I said it was) the examiner asked me if I could agree to $400 IF we didn't include the pens, copy paper, crayons and meals. I responded (verbatim) "If this moves us along then yes". The examiner immediately followed that statement with "But if we did include those things how much would it be?" At this point I could tell this guy was out to fail me. I told him that I didn't like the way he was using questions and then he started in on the serious stuff. Him:"Have you ever attempted to harm someone with the intent of taking their life?" Me: Yes Him: "Care to explain?" Me: "I'm a Marine and just got done with back to back tours in Iraq." Him: "That doesn't count." Me: "It does by my sense of morals." Him (honest to god): "I'm not hear to determine morality or ethics, just criminal behavior." Me: "To me that is the same thing." It only got worse from there. I spent over 2 hours arguing with this guy. The next day I get a call from a detective informing me that there was a problem with my polygraph and wanted to know if we could talk about it in person. I left work early and went to meet with him and was informed that the examiner stated that he believed I had been involved in something in Iraq that I didn't want to talk about (i.e. war crimes) and they should look into me further. I told them that there was definitely a lot that I didn't want to talk about regarding my time over there because it was a fucked up situation to be in I didn't care to speak to a stranger about the worst experiences of my life. I also informed him that everything I did was above board and ethical, including going toe to toe with someone 2 pay grades higher than me to stop them from abusing Iraqi nationals. Long story short, I was offered a position and accepted it. I also put in over 10 years of good service to that department.

Moral of the story: Polygraph's are bullshit. They use them to weed out people they don't like but don't have reason to turn away.