"Eric, from Hong Kong, began watching secretly filmed videos as a teenager, attracted by how 'raw' the footage was.

'What drew me in is the fact that the people don't know they're being filmed,' says Eric, now in his 30s. 'I think traditional porn feels very staged, very fake.'"

China gives me the impression that they would take these incidents seriously and punish the perpetrators. I can see how they deal with drug related crimes.

So I wonder what the authorities did here. Was this even reported to them?

Retroreflective and RF often miss them. Thermal gets them every time. No microcam runs at ambient temperature. The better Type-C phone attachment ones from HIKMICRO work.

How do people prevent this? I have yet to find a device or tool that would discover such hidden cameras.

https://archive.ph/CrS1Q

In 2002, I took a guide-led "Spring Tour" semi-off-season trip with some college friends. There was one sketchy, bougie colonial-era hotel near Shenzhen where the rooms came with young women "masseuses". (Eww.) I assumed there were cameras in the room and turned that down. The structure was old, kept up, and beyond opulent. Indoor and outdoor shooting ranges. Hedge maze. Bungalow-villas.

There and elsewhere, I learned why there were so many "karaoke" bars. Probably things have changed, I hope.

It would be very easy to do this in nearly any hotel that has no-click or simple click-through WiFi. A tiny box affixed to the back of the TV set, or someone opening up the clock radios that most Hotels still have and adding a camera and an ESP-32.

Hotels should look for devices that seem to stay on their wifi for a long time.

Of course, if it's profitable you can just use a cell modem and pay for the service and not be on the hotel WiFi

Spanish don't mess around in this matter. You have outright Prosegur or some other security company's cameras openly in your Booking/Airbnb apartment and a word of the host that "it's not recording". Creeps in Prosegur monitoring center getting to watch the action for free.