A Chinese detective’s tips on how to protect yourself from spy cameras in offices and hotels

China has seen a surge in criminal cases involving hidden cameras in hotel rooms and rented flats. Once only accessible to private investigators or big companies, hidden spy devices have become more affordable as well as more advanced and harder to detect, leading to misuse. He Zhihui worked as a private detective in the early 2000s. But when the Chinese government outlawed the profession in 2009, he flipped his job to become a counter-surveillance expert.