Should I tell the truth?

[secretive1]

Technically you did admit to most of your indiscretions up front, so you weren't really covering anything else up that was major.

That is rather odd that they would ask you after the test if you looked at "explicit images".  What is even stranger is that they did not ask you about illegal sexual activity before or during the polygraph.  It must not have been law enforcement screening, or the interviewer did not do a very good job.  Sounds like you didn't go through a thorough background investigation either, if all they did was just talk to a few neighbours and friends.

The psych evaluation sounds even more strange, if you were asked about prostitution, but not drug use.

In the end you ended up not taking the job, which again just goes to show that it wasn't meant to happen for you; whether for one reason or another.

During my pre-polygraph screening AND the psych screening (which was after my poly), I was asked about drugs and illegal sex acts.  In both cases I gave them the same information about pot use (my "fudge" numbers) and gave a straight "no" to the illegal sex acts.  In both cases they also asked the usual questions on crime, computers, foreign contacts, overthrowing the government, etc.  The psych test also asked about my emotional stability, family history, and other crap as the shrink was just prying into my head trying to see if I was mentally stable.  However in the polygraph, they only focus on a few things and tell you what questions will be asked before hand.  Apparently this makes the polygraph more "effective" according to my research.  The pre-polygraph screening must have made them think that they should focus on crime and computer use for me during my poly.  I never opened the door made them even the slightest bit suspicious about my sex life.  I happily admitted to being a guy who looks at porn at home, the usual, but never anything illegal. 

The polygraph question regarding "serious crimes" is pretty much a cover-all question.   There is really no reason to ask any other questions during a poly.  If a person is single, then technically they won't feel guilty about sleeping around.  If a person is married, they may feel guilty about it.  But the crime question technically can include prostitution, drugs, foreign conspiracies, computer hacking, etc.  So they really try to drill most poeople on crime.  They didn't hone in on anything specific because they wanted me to lead them down some path in my guilty conscious, which I was not going to do!  The polygraphers don't have time to specifically ask you about every crime in the world, so they are vague, and want you to start talking and spilling your guts.  I was too smart for that.

I'm glad I didn't take the job because now I feel I have more control over my life.