There was once a case in Indonesia where the video of the celebrities changing clothes in the changing room was being exposed to the public. It was known that the mirror is actually a 2 way mirror, means not only we can see our reflection but also the person behind the mirror can see us while we can’t see him.There is a way to check whether it’s a normal mirror or 2 way mirror. Put the nail on the mirror surface. If there is a gap between the nail and the nail’s reflection, that means you are safe because it’s a normal mirror. But if the nail touch the reflection directly, be careful because it is a 2 way mirror.
I always practice this while in the public toilet or changing room. Be extra careful is better than find out the video or pictures of yourself naked while changing, around the cyber space.