For most people the best way to “beat” it is to just not admit to anything. Here is my personal experience.
Many years ago, my work would do random lie detector tests. It was a large national chain, and in the five years I was there, they only came to our store once. All management was tested, so I got the honor of seeing it first hand.
In my opinion the lie detector was more of a prop than anything else. They bring you to an office, strap you in, and let you sit there a while. Then they came in and explained the serious consequences that could happen if you were not being truthful. They even said they would rather help people than get them in trouble, so if there was anything you wanted to “explain” first now was the time.
Then the test. I knew I didn’t do anything wrong, so I wasn’t concerned. They asked the expected questions, and I answered them truthfully. When the tester was finished he said there were a few responses that he was “concerned” about. He wanted me to take a few minutes to think about my answers, and left the room. When he came back, he again gave me the chance to “come clean.” Then he asked the most incriminating (sp?) questions again… another chance to confess… then it was over. I passed and kept my job.
Others however didn’t do as well. There was a group of warehouse workers who admitted to smoking a joint with a truck driver. There were five people involved including their manager. Four admitted to doing it (same tactic as was used on me), but the manager continued to deny it even when directly confronted. Four were fired (actually resigned to avoid “prosecution”)… the manager was not, because he knew that the results would not stand up in court against him, and the company wasn’t really willing to go that far.