You can tell if it's a 2 way mirror by shining a light on it and by knocking on it gently.
When you shine a light on a two way mirror you will be able to see the other side of the mirror.
But if the mirror is a one way mirror and you shine a light on it you will see your reflection and the reflection of the light.
However a better way to tell if a mirror is a two way mirror or not is to knock on the mirror gently.
If you knock on the mirror gently and there is a hollow sound going on instead of a more solid sound, it is possible that the area behind the mirror is open instead of the mirror being just mounted to the wall.
This could reveal that there is an observation area or a camera behind the mirror.
However if you're in a reputable motel or hotel then it's very unlikely that anyone is watching you and very unlikely that the mirror is a two way mirror.
People check hotel mirrors to see if there may be a camera and to see if the hotel mirror is a 2 way mirror or not.
With a camera hidden in or behind the mirror or if the hotel mirror is a 2 way mirror it can be that someone is watching the person or people in the hotel room and can also gather a persons sensitive or personal information without the knowledge or consent of the people being observed.
It's very rare that a hotel mirror would have a camera or be a 2 way mirror though.
To check a hotel mirror touch the mirror with your fingertip and if there isn't a gap between your fingertip and the reflection, it's probably a two-way mirror.
At this point, you can try to take the mirror off of the wall or keep searching for a hidden camera.
Hotel rooms are intended to be private places and the idea that someone could be watching you is unsettling.
As you may assume, there are indeed laws surrounding the use of hidden recording devices in private areas.
In the United States, it is not legal to record hotel guests in their private spaces without their consent.