Hidden camera detection?

Recently saw in the news about some hidden cameras.  As I recall the most recent were a couple different cases involving AirBnB sites.  The program mentioned there were detectors available to help locate them from the RF for the wireless signal.  This assumes that they are wireless of course - I think that is often the case but not always.
 
I dug out a ham field strength meter so see if it would detect anything.  Even right by my router it didn't show anything but these are made for much higher signal levels - up to 1000 W - and the frequency is lower too so not too surprising.
 
There are a number of units on Amazon for around $20.  Does anyone have any experience with these or could suggest a good unit?

If you are renting an AirBnB and expect the camera to be wireless, I really wouldn't count on that. It also may be a Wi-Fi camera, or if your talking CIA quality cameras, it could use cellular. Wi-Fi uses two frequency bands and cellular can use many, at least 20.  If you expect a $20 detector to find them all, your joking, right? 
 
If it was me, I would forget about finding the RF because in this world, RF is everywhere. But cameras use IR to see in the dark, and any camera which would work in the dark projects IR, which can be picked up pretty easily.  Turn out the lights, and use a cheap B&W camera, and if there is IR, the camera should easily be able to find it.  Maybe their camera doesn't use IR? Possibly, in that case just turn out the lights if you don't want to be spied upon.
 
This all won't help with thermal imaging cameras which don't emit IR and can see in the dark, but those are really expensive, so we can rule-those-out.

Relating to rentals in general of condos and homes I have seen use of remote monitoring and control and cameras now for over 20 years.
 
Detection of an RF stuff has become mostly cheaper over the years.
 
That said there are devices that use triggers to be enabled (always been around) - sound or motion or light - so that one can be passive, active or wired (not RF).
 
BTW Airbnb recommends the use of video cameras today. (recommendations do not include bedrooms and bathrooms though).

pete_c said:

BTW Airbnb recommends the use of video cameras today. (recommendations do not include bedrooms and bathrooms though).

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Does AirBnB require that the homeowner disclose cameras to the renter? 

I do not know.
 
I have seen renters totally destroying homes and condos and really not caring much.
 
Or say like two people renting a place and 10 people staying there.
 
So the surveillance is pushed a bit as a validation or confirmation of who is renting.

There are 2 things that can be detected with many cameras, the wireless  frequency (might be able to sniff the IP, if IP) and possibly IR as many cameras turn on IR when it gets dark.

There are 2 things that can be detected with many cameras, the wireless  frequency (might be able to sniff the IP, if IP) and possibly IR as many cameras turn on IR when it gets dark.

ano said:

Does AirBnB require that the homeowner disclose cameras to the renter?

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Yes, they do.
 
https://www.airbnb.com/help/article/887/what-are-airbnb-s-rules-about-electronic-surveillance-devices-in-listings