Although I know it's not a cop detector, I definitely proved to myself last night that leaving my detector on when I'm not driving can't hurt. Parked my car on a relatively quiet suburban road preparing for some less than legal activities, and apparently somebody must've called the cops. About five minutes after parking there the detector starts beeping every few seconds. I quickly walk across the street to a parking lot and sure enough two LEOs, one marked and one unmarked, drive right past my car about 40 seconds later. Silly suburban cops running c/o in the middle of the night with no cars around.