Interesting. I would not think that the examiner would discuss the results with the person taking a polygraph during an investigation, unless they already figure that the person they're testing is not involved. I'm also told that a lot depends on the examiner. Most small town agencies don't employ their own, they use one from another bigger county or the state LE, or the FBI. Good ones are very expensive, and every hour they spend testing a subject costs the agency money. I don't think they would waste money on retesting someone in hopes they 'get it right.' I know those are my words, not yours, but I'm trying to justify the suggestion that the examiner would adjust the questions to accommodate the person taking the test, in a criminal investigation. I really don't see why they would, if they're trying to get to the truth.
One thing to remember, they do not ask open-ended questions, they are all yes or no questions. There's not much you can do to qualify a yes or no answer. "Yes, but.... " The answer is still yes, all you're doing is giving a reason. They don't care about the reason right then, only your answer.
(You, meant generally, not personally.)
I was required to take one for a job in a supermarket years ago. Scared me half to death. I was never told the results, but was allowed to keep the job, (I had already been hired and was in training) so I figured I must have passed.