My detector has actually saved me from two tickets.
One because I was inadvertently speeding when the detector went off. I got pulled over in a safe spot before the cop even got turned around. When he got to my car, the first words out of his mouth were, "What happened?" I told the truth and admitted I had no reason to complain about getting a ticket. He laughed and let me go with a written warning.
On the second one, I wasn't speeding but the cop told one lie after another. I had my fiance' and sister in my vehicle at the time. I explained to him how the waters were parted and my rant ended with an invitation to write the ticket, so I and my two witnesses could enjoy watching the judge bust his chops. He let me go with a sheepish, "Watch your speed."