First, we examined the rooms using the easiest and cheapest method of all: the “naked eye” test.

My colleague, Victor Loh, went from room to room, noting that nothing seemed out of place or suspicious. After 20 minutes of searching, he found one camera embedded inside a working clock — tipped off because the time was wrong.

“I found one,” he said. “But it’s so well camouflaged.”

Cost: $0 | Cameras found: 1

For this round, Victor downloaded a popular app called Fing, which scans Wi-Fi networks for cameras. He also used his phone’s flashlight to make it easier to see camera lenses, a common online recommendation.

The app showed 22 devices were connected to the home’s Wi-Fi — but no cameras.

Tjia explained that when members of his team set up the cameras in the house, they also set up a second wireless network. They then connected the hidden cameras to that network, bypassing the home’s main network.

“Even if we didn’t do this, the app would show cameras are in the house, but not where they are located,” he said.

Victor had better luck using his phone’s flashlight. With it, he found three more cameras — in a Wi-Fi repeater, a shirt button and a teddy bear — the last one, like the clock, catching his eye because of something amiss.

“It’s not grammatically correct,” he said of the bear’s T-shirt, before finding a camera behind one of its eyes.

Tjia said most hidden cameras are made in China, where, ironically, they are banned.  

Cost: $25/year for app subscription | Cameras found: 3

Next up: a basic lens detector, which is cheap, portable and easy to use. The device emits infrared light, which reflects back from a camera lens as a red dot.

The problem? You must be close to the camera for it to work.

Despite its popularity online, Victor found only two cameras with this device — one in an essential oil diffuser, and the other in a Wi-Fi mesh device.

Cost: $50 | Cameras found: 2

In total, Victor found 17 out of 27 cameras — not a bad result, but not a great one either, especially given the time he spent locating them.

“When you are traveling, you are really exhausted,” he said. “The last thing you want to do is spend … one hour scrutinizing every nook and cranny just to locate a camera.”

Social media posts about hidden cameras have increased nearly 400% in the past two years, according to the data company Sprout Social — with countless articles dedicated to finding a quick and easy solution to the growing problem.

But in this cat-and-mouse game, the cameras have the upper hand, said Tjia.

The detecting devices are getting better, but so are the cameras being hidden, he said.