How do China's overseas personal shoppers manage to smuggle luxury goods into the country without being detected by customs?
A sex scandal involving a high-ranking customs official at a major port may have provided some insight into an aspect of the trade, believed to be worth as much as $136 million (US$100 million) per year.
Guan Zhaojin, the former head of customs at Dalian port in northeastern China, is accused of having affairs with several overseas shoppers - known as daigou in Mandarin - and of abusing his power by helping them and several customs staff to evade inspections and customs duty.
Guan was reported to the authorities for smuggling and corruption last August by his wife, who also filmed him confessing to affairs with several women in a video that was later leaked online, news site Red Star News reported on Monday.
The woman, who was not named in the report, confirmed that the man in the video - wearing only a pair of underpants - was her husband and Dalian's top customs official.
Guan has been suspended from his job and his conduct is being investigated, according to Dalian Customs.
"We have received new leads and online reaction concerning Guan Zhaojin's cover-up and assisting with smuggling, corruption and bribery," the authority said in an official Weibo announcement on Sunday.
"Dalian Customs attaches great importance to this, and has decided to follow the discipline and inspection programme's requirements to carry out an investigation."
According to Red Star News, Guan denied the affairs and said he was cleared of any wrongdoing by Dalian Customs last September.
"They cleared me. Now my workplace is conducting another investigation and I will await the results. I believe I will be cleared," Guan was quoted as saying.
"I will take to the courts to prove my innocence and co-operate with the investigation."
Daigou have thrived in recent years, as more consumers have turned to buying luxury goods and products like baby milk formula from overseas, where they are often much cheaper, due to China's heavy import tariffs of 30 per cent to 80 per cent.
Daigou, who are often Chinese citizens living abroad selling to friends and trusted clients through WeChat, also act as key influencers for foreign brands among consumers, often stopping sales of a particular brand after it has encountered controversy in China.
But daigou have sometimes earned a bad reputation in countries such as Australia, where their activities have led to chronic shortages of baby milk formula for local consumers.
Recently, Chinese authorities have clamped down hard on the previously unregulated trade via a new e-commerce law that requires daigou to register as businesses subject to taxation.
There are no official figures on the total value of undeclared foreign luxury goods brought into China, but Bloomberg estimated that last year's imports amounted to US$100 million.
This article was first published in South China Morning Post.