Over a 22-year period, Robert Hanssen, one of the most notorious spies in US history, passed several polygraph tests during his tenure at the FBI while he also sold secrets to Russia.
Both hanssen and Ames came up inconclusive in their polys. But they were able to cleverly explain them away. Coming up inconclusive is easy, passing outright is hard. To get a job at an intel shop you must pass. The problem with Ames and hanssen was in the organization, not the poly.
