Radar Detector / Jammer

I'd appreciate any insight on the results or opinions of different types of detectors or radar jammers. I have read that the laser needs to hit a flat spot on the target. If that is true it is difficult on most Corvettes... I have a C5. I've seen in Ecklers a product which covers the license plate and is supposed to difuse an incoming laser signal.

Any thoughts on these?

Thanks and Happy New Year!
Dom