I think it probably works much better when the "bad guys" KNOW they are being watched, don't you?
That's what flying reconnaissance platforms is all about. The "bad guys" KNOW they are being watched. So, it tends to help them refrain from doing "bad things". However, if they decide to go ahead and do "bad things" anyway, at least you know it as soon as possible.
Throughout the Cold War both sides used reconnaissance platforms to watch the other side and both sides knew it was going on. Helps to keep the peace.
Apache, was your Dad 55SRW? RB-47's?