FYI, a poly - which you said you've taken before - isn't about whether or not every document you've ever filled out is 100% accurate. It's the big pieces. Have you intentionally lied on your application? Were you truthful about your criminal history, drug use, etc? If you're honest during the application process, you should have no issues. The examiner asks about your logbook? "Yes, I gave the best numbers I could, given that I logged tach at first, etc. etc. etc." At the end of the day, the question is: did you say/do something with the intent to deceive? If the answer is no, then you're fine. If you're inflating hours and fabricating stuff, then that's a different answer. You're the only one who will know the truth, and it'll be up to the polygrapher to figure out whether your statements match the facts.
'Nuff said?