The point is to start gaming the system at the screening process, and not necessarily by beating the polygraph then. There are two obvious qualifications for contestants: they have intentions, beliefs, or past deeds of which they are ashamed, and a polygraph would indicate this when they're questioned. Presumably those are the qualities they screen for.
Possible ways to game the system:
* Have a sordid past/inner life, be willing to admit it all, but convince them in the preliminaries that you're mortified by it all. Rack up money by gleefully throwing yourself under the bus.
* Have a sordid past/inner life, but beat the studio polygraph (and ONLY the studio polygraph) so you can get the money without eternal shame.
* Convince the screeners you have a sordid past/inner life by triggering false positives, then show up and play innocent.
Doesn't sound that hard. This is a job for the collective powers of Evilbore if I ever saw one. I'm willing to take a mere 10% cut as the original idea man, the Verbal Kint if you will.