I've used a radar detector for many years, ever since they became available. There are times when they work just fine. But, other times certain RF, Radio Frequencies, set them off when there are no radar police around. That drives you nuts when that happens; because even if you know the signal is false, the noise is awful.
Other times the police use a highly directional radar gun, and they only apply it momentarily, and infrequently, so if you hear it, it is probably too late. One has to learn to interpret the signals received with it, and differentiate the false signals from the real ones. There is a knack to it.
The Radar Detector is best used on the open highway where even a momentary blip from the police radar registers when you are still out of range, and they are aiming at another car a mile or so in front of you. Then you know that the police are working that stretch of highway, and you can slow down well in advance. (The transmitted signal is strong, but the received signal returned to the police is an echo bouncing off your car, so it is thousands of times weaker than the raw signal that your radar detector sees. That's why the range of the radar detector is many times greater than the police radar.)
Some people have experimented with "ECM", Electronic Counter Measures, like military aircraft use. Those generate false radar signals, jamming, back at the police, and that cancels out their radar.

Running a game on the police like that could have unpleasant consequences, so I wouldn't do it.

The police are always getting newer and better equipment, and sooner or later they will catch you.
Get the GPS, and forget the Radar Detector, even those devices that also have the laser detector. It's not worth it, and you'll receive more satisfaction from the GPS. :wink: