I have gotten out of several tickets with a (cheap) detector hanging on the window. One time the cop asked me if it went off and why I did not slow down. I told him I was coming home from working all night and just ignored it because I was tired. He said, "Yeah, after a while you tend to start ignoring them." Then he let me off with a warning. Most officers don't take them all that seriously, it seems.
The only tickets I've had in the past 5 years were speed traps and they weren't giving out warnings to anyone. Once on the interstate passing through Indiana, at least 10 cops waiting for suckers coming around the bend. The other time, a speed "detail" using laser from the top of an on ramp with several chase cars staged. That time the LEO actually apologized that he could not give me a "pass". And I did not even suggest it.
With the sharp rake of the SHOs windshield, I find you can mount it to the left of the rear view mirror and get good reception, plus still use the visor. Added bonus is the visor hides the unit from behind in a pinch. Most importantly it is directly in your line of sight, making it much easier to react.