One may spy on every subject, but cannot spy other's mind.

Spy ***Under the skySomeone's eyesContinuously spy

If the security officials of any place, run the marriage agencies, just to spy and cheat own people than giving them security; does anything stay there, or any moral, legal, and standard way, to legitimise that?

One may spy every subject, but cannot spy other's mind.

The spy is such a way where you target your hunting. If you fail, it is the severe humiliation of you, stop that, and accept the defeat than going forward to nothing.