There are camera which are smaller in size that could capture HD videos and possibly hides its presence from Human eye. So conduct this simple test to check whether you are really "Private" with no hidden cameras monitoring.
- Enter trial room with your mobile phone and ensure mobile signal to make calls.
- Try to make call inside the private room, if there is a "Hidden Camera" you cannot make calls due to interference of fiber optics during signal transfer which blocks mobile callls. (sic)
- Making calls without any interference is the sign of Camera free room.
This is total nonsense of course, but sadly, many trusting souls will believe it. If you really need to make sure your "expectation of privacy" areas are free from spy cameras, may I suggest spycamdetection.training.