I had recently went on a ride along with a police station, while down there in the offices, I ran into a CVSA/Polygraph tester. We got to talking, I told him I knew what I was talking about. Once I proved this to him, he told me they all know it's BS and that CVSA can easily be conquered as well as polygraph and that he had messed with it and proven it himself. He said the one key to both is just not to give a crap. Just go in with no worries. I think it's funny though that he told me none of the polygraphers in this large city (more then 1 million people population) believe that it works and they really dont give  a crap.