I read about a spray, that when applied to the license plate would have too much of a glare to be photo'd.
they tested the paints and many, many other voodoo methods of shielding your plates on Mythbusters.
BUSTED them all!
As for me, I don't mind them since I STOP at red lights. Imagine that!
Actually I tend to WELCOME them in StL, since they usually tend to go up at intersections where I would routinely see 3-4 cars go through on a red after the lights changed. Cameras go in, and a few days later the scofflaws have mysteriously stopped cold-turkey. Funny how that works.
though at one intersection I do miss seeing the badass motorcycle cop who would hide behind the bushes in the park on the corner and tear out chasing them down.. Very fun to watch. That dude had some mad riding skillz.