Always felt I was being watched.

Also always felt some people don't realize they ARE being watched.
What I mean by this? Have you ever watched someone through a reflection of a window or mirror? It doesn't seem likely that you can be seen by the angles but you never know.

Here is an example, My living room glass door opens inward and I can be sitting in a chair opposite side of the room. I can see in the glass reflection if a delivery person is walking up my driveway but they would never see me.