Just because the cops not shooting doesn't mean the detector will not work. My cousin has a really nice one that does Radar,Laser, and LIDAR, as well as Jams LIDAR. He tested it by driving past some parked cruisers at Dunkin Donuts and it went off. He did the same with one of the baseball teams detectors, passing it while it was not shooting, the dectector still got a signal at a good distance away. Its great at finding fast foods places too because their microwaves set off the detector.
I never got one because I don't speed much, my truck stinks on gas as it is. The one time I did go well over I got caught. (i was late for thanksgiving dinner and was doin 77 in a 50.)But the cop was nice enough to only write me up for 10 over because it was my birthday. Fine would have been $350+ and maybe a loss of my liscence. Instead I think I paid $80.