Polyfool,

Yes, the post-test commentary/accusation(s) regarding control question material by polygraphers does give them some protection from any quality control review (hehe) changes in the outcome.  In general, since they have gone to the trouble of "setting" these question areas and have intentionally gotten the examinee to limit any admissions during the pretest phase, they (the examiners) will not further question an examinee regarding this material during the in-test phase.  This is not true of relevant question material.  They will bluff/accuse/fish/etc throughout the process about relevant issues up and until they pronounce that they don't see any problems for a no-deception-indicated (NDI) scored examinee.  In general if you fail their test you are interrogated about the  relevant material; if you pass their test, you are told that you appear to have passed, but that you seem to have some problems with the control material.  They, of course, don't realize at that point that you know the difference between relevant and control questions and won't refer to this material as control, but being the knowledgeable person you are, you will know.