[a] Take a look at the size of the lens on the back of your mobile phone. That's how small high-quality cameras already are today.
But, a hardwired camera with no active illumination, behind an opaque sheet of IR transparent plastic (basically the kind of plastic on many modern electronics) would be incredibly hard to detect (without tearing everything apart).
There are certainly devices that can detect localised electric fields, wireless transmissions or make it relatively easy to spot shiny surfaces (such as camera lenses).
…but, and I say this with absolute confidence; there is no device that exists that can detect if you are being observed or not.
So, to some degree, it may be possible to find common wireless cameras, and if you’re some DIY house owner installing their SPY PRO secret camera from Amazon for $50, you can probably find it.
…but, the point the parent comment is making is that there are, and, increasingly will be, cameras you won’t be able to detect.
You’re best off to operate under the assumption you are being filmed when you hire a house, and, increasingly, just when you go around your daily life.
https://en.wikipedia.org/wiki/Sensitive_compartmented_inform...
Can you give me just about one example besides some creep who spied on his guests?
I don't think that cameras in hotel rooms are in any way city dependent.
I specifically excluded the creepy owner or manager who spies on guests.
Was it worth installing the CCTV?
Or entertain them.