You are correct, they pick up a lot. But depending on the type of engagement, you just end up taking apart every single thing with a circuit in it anyway. Ther

You are correct, they pick up a lot. But depending on the type of engagement, you just end up taking apart every single thing with a circuit in it anyway. There are defeats for nonlinear detectors, like a three port circulator with a resistor. In turn there are more advanced detection methods, but now you are getting in to tools not publicly available.