I had a good radar detector a few years ago and gave up with them - too many false signals and too much false security. I now live in MD and go in to DC and VA a lot - radar detectors are illegal in the latter two states. We have lots of fixed speeding cameras and roving vans with speeding cameras. Plus the usual police on the road. I made the decision that if I'm not paying enough attention to spot the speed trap, then I deserve the ticket (none so far, except two from fixed cameras in heavy traffic, when the cameras were new).
By biggest fear is pacing at night - when you're driving along on a busy road in the dark, it is pretty hard to tell that the guy behind you can give you a ticket. Radar/laser detectors don't help with pacing. I've been stopped once due to being paced by a following officer. Fortunately, I was able to convince him to let me off with a warning.