How to determine if a mirror are 2 way or not (Not a Joke!) Not to scare you, but to make you aware. A policewoman who travels all over the US and gives seminars and techniques for businesswomen passed this on. HOW TO DETECT A 2-WAY MIRROR : When we visit toilets, bathrooms, hotel rooms, changing rooms, etc. How many of you know for sure that the seemingly ordinary mirror hanging on the wall is a real mirror, or actually a 2-way mirror(i.e., they can see you, but you can't see them). There have been many cases of people installing 2- way mirrors in female changing rooms. It is very difficult to positively identify the surface by just looking at it. So, how do we determine with any amount of certainty what type of mirror we are looking at? Just conduct this simple test: Place the tip of your fingernail against the reflective surface and if there is a GAP between your fingernail and the image of the nail, then it is a GENUINE mirror. However, i f your fingernail DIRECTLY TOUCHES the image of your nail, then BEWARE, FOR IT IS A 2- WAY MIRROR! So remember, every time you see a mirror, do the "fingernail test." It doesn't cost you anything. It is simple to do, and it might save you from getting "visually raped"! This is a really good thing to do. The reason there is a gap on a real mirror, is because the silver is on the back of the mirror UNDER the glass. As a two-way mirror, the silver is on the surface. Keep it in mind!