Over a cup of tea in Phnom Penh recently, some mates were telling me how hard it is to guard against scams in card rooms back home. Sure enough, police in Yueyang’s Louxing district, Hunan province, put out a notice about just that sort of thing a few days ago. Back in June, cyber police picking up clues online discovered that people were using wiretapping and secret-filming gear inside some downtown mahjong parlors and teahouses, turning card games into rigged setups where someone always wins.

Local police launched an investigation and uncovered a criminal gang led by a man surnamed Dai. This crew specialized in selling peeping tech, and they would quietly sneak into teahouse private rooms around town, hiding miniature cameras and audio pickups in every nook and cranny. Players sitting at the table didn't have a clue that the cards in their hands and the expressions on their faces were already being broadcast completely to a backroom operator.

Sitting in front of computer screens acting as "analysts," the folks in the backroom watched closely and passed key info along to their accomplices on the floor via phone or internet. The players on the scene wore tiny earpieces, listening to instructions on when to meld or when to win. On the night of August 26, local police stations teamed up with multiple units to raid three dens, nabbed 11 suspects, and seized several computers and pieces of criminal equipment. Neighbors just playing cards for a bit of fun never imagined that hidden cameras and gear were lurking in the corners of their private rooms.