Beware while using the trial rooms

Just received this in mail.

Beware while using the trial rooms any where.

HI All,

How to determine if a mirror is 2 way or not ? (Not a Joke!)
Not to scare you, but to make sure that you aware. Many of the Hotels and Textile showrooms cheat the customers this way.

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 or bathroom or bedrooms.
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?

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, if your fingernail DIRECTLY TOUCHES the image of your nail, then BEWARE, IT IS A 2-WAY MIRROR! (There may be someone seeing you from the other side).. So remember, every time you see a mirror, do the 'fingernail test.' It doesn't cost you anything. It is simple to do.

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.
Whereas with a two-way mirror, the silver is on the surface. Keep it in mind! Make sure and check every time you enter in hotel rooms.