Breeze,
You said,
And Brian, I do not know any agency that uses polygraph as the sole hiring criteria.  Regardless of what you read on these pages, I know for fact that what is used is much more of a whole person approach.  Polygraph has however become the lightning rod of the hiring process, and a way to subjectively dismiss an otherwise acceptable applicant as "not within parameters". This is my belief anyway.

That is the whole point about the polygraph.
The USSS and the FBI absolutely use this as the sole criteria.  I know this firsthand, and also from other FBI sources.  The USSS states in their conditional offer of employment that the offer is conditional to passing a polygraph examination.  When at the same time they lie and state in the paper, Washinghton Post author Bill Miller, that the polygraph will not itself eliminate an applicant.