I don't feel I have ever been targeted as crew, anywhere. It's usually just the next person to walk past.
It takes 15 seconds, and usually the screener has a quick chat. Some of them are a bit over the top, but generally they are fair people.
Doesn't change the fact that it is a total waste of time to perform this test on flight crew. But I believe most of them know how stupid it is and treat it with the seriousness it deeserves.