Offering freebies is just one of the marketing strategies used by health supplement salespeople to persuade the elderly to buy their products.

In a 2016 report by Shanghai Television, a reporter went undercover to work as a salesperson at a popular health products company and discovered the company's sales training notes, which read: "Talk one-on-one with the elderly; talk about illness, and let them pay attention to it; introduce the products that help lessen the illness; give them promotions; sound like an expert; make home visits; move them and surprise them."

Besides daily lectures, many of the health product sales companies also organize big events in hotels or free sightseeing trips to attract seniors.

In November, Hao Ruxiang, deputy director of the industry and commerce administration in Shuozhou, Shanxi province, led a joint raid on an illegal health supplement sales event in the city.

The grey-haired Hao, 54, said he was approached by a salesperson on his way back from work, asking him to join a four-day health lecture in a local hotel.

"They told me I could get 10 eggs for free if I went," Hao told CCTV. "I knew there was something behind it at once. I have dealt with so many similar cases."

The next day, Hao went undercover to the lecture, and saw some 500 elderly people in the venue, listening to a lecturer who claimed to be a graduate from Beijing Medical University and who bragged about the therapeutic effect of a product in tackling hypertension and high levels of blood sugar. Hao secretly took videos to avoid being discovered by security guards who stopped people from using smartphones.

After having collected enough evidence of false and exaggerated advertising, Hao led a team of 80 officers from his office, the police, and the local food and drug administration to detain the sales group at the hotel when they started selling their products on the last day of the event.

When confronted by Hao, the lecturer confessed that his degree was fake and that he had learned all his health theories from the internet. The organizer was given five days of administrative detention - an extrajudicial punishment - and the money taken was returned to the elderly people.