At another forum several years ago there was a long post about this subject. A guard of a rural prison said they were issued one of them for escaped convicts. He said they use to test them by doing live runs, via using real people, and they were a POS. They gave false positives, ie, showing a hit when there was nothing there and also couldn't pick up a warm body when in fact it was within operating distance.
That was then. Maybe now they have something different. I don't know.
Infra red game finders...
