Letter from Beijing/Mark Godfrey: No loud shirts or screaming sports cars, private investigators in China tread softly, while the legal status of their work remains as unsure as their public image.
At another time the local communist party neighbourhood committee or an individual's work committee could have quickly spotted adultery, but in today's China the local party secretary no longer issues the certificates of infidelity needed by the courts to grant a divorce.
Hence the advent of a new character in Beijing's alley-ways - the private investigator.
China's State Council decided last August to simplify marriage and divorce procedures, allowing couples to get married without the permission of their danwei, or work unit. Identity cards and residency documents now suffice.
The procedure towards a divorce was similarly simplified. In April 2001 the principle of "at fault" was introduced to Chinese marriage law, allowing wronged spouses to sue the partner responsible for the break-up of the marriage. The "four faults" now accepted by the court are adultery, bigamy, abuse of a family member and abandonment of family. The revised marriage law has created work for China's fledgling private investigation business - but many investigators get their work elsewhere.
"Investigation companies specialise," says Zhang Yongtu, a private investigator in the southerly Sichuan province. "Some of them are good at protecting companies' intellectual property rights through cracking down on fake products, and others are famous for insurance fraud cases or obtaining legal evidence in family cases." More freedom of movement and the replacement of well-supervised housing compounds with apartment blocks has made the red-armbanded supervisors of the neighbourhood committees novelties in all but the traditional hutong cottage housing still standing in pockets around the city.
Private investigation companies thrive in China's more anonymous society, but they remain suspicious in the eyes of the state. In 1993, the ministry of public security banned private detective firms in China, worried at possible interference with state security services. The Supreme Court reversed that decision in 2002. But as the sector becomes more crowded, private investigators are seeking a proper licensing system from the state.
Private investigators are also restrained in the techniques they are allowed to use. The 2002 decision opens the courtroom to tape and video evidence acquired in secret, but neither tape nor video can be used as a bug in a private home.
Shanghai's 200-plus private investigation firms meanwhile trail wife-cheaters, bigamists and straying wives. China's best- known private investigator, Wei Wujun has featured in countless TV and magazine features in China, and charges 2,000 - 3,000 yuan (€215 - €317) for a day's gum-shoe work. Wei Wujun, meanwhile, puts his expertise down to watching US films and detective shows like Colombo. His clients often get their inspiration to hire him from the same source.
State-sponsored moralism is still enforced in China's cities, but often intermittently. Beijing's Public Security Bureau, or police department, periodically announces ritual crackdown on "social crimes" such as prostitution and gambling. The bureau announced recently it had swooped on 21 prostitution or gambling dens as well as 18 "entertainment venues" which also offered "pornographic services". However, prostitution is openly visible across Beijing, with massage parlours which are staffed by young prostitutes mostly drawn from the ranks of the dagongmei - women from rural areas who migrate to cities like Beijing in search of work.
For most ordinary Chinese, private investigators are low-life characters straight out of fiction, using telephoto lens and electronic bugs to invade the privacy of individuals and catch adulterous people in the act for their lovelorn clients.
The reality is much less glamorous, or sordid, than most people imagine, insists Shi Lijun, a private investigator working in Beijing for the past nine years.
"Actually, most of our clients are firms rather than individuals, and there is very little spying on would-be adulterers," says Shi.
"Our main work is to help companies to collect evidence for commercial purposes, such as checking credit-worthiness and for business feasibility studies.
"It's all very respectable work and far removed from fiction. There are investigators who will take on domestic cases, but I think the majority are wary of getting involved if it could turn out to be a real mess," he says.
Most of China's private investigator businesses are small-scale operations, explains Shi, a mix of talented and hapless operatives.
"Some are untrained and unemployed, people who need the work after losing their job in the shake-up of state enterprises."
The need for them has also arisen after the demise of neighbourhood watch organisations and neighbourhood committees set up after the Communist Party took power in 1949. Alley-ways and housing complexes were supervised by "bound-feet detectives," a nickname given to ageing busybodies who regularly staffed the committees. As well as disseminating government propaganda, the watch groups regularly intervened in family squabbles and supervised the country's strict one-child policy and house residential system, limiting citizens from moving around. Crime rates were understandably low.
Today there are more than 700 investigative firms legally registered with the State Administration for Industry and Commerce, according to private investigator Zheng Gang. The appearance of government officials as well as representatives of foreign security and investigation companies at a recent conference on the industry - a first for China - hints at the potential of the investigation and security business.
"It is because of my evidence that a secret fake goods warehouse in Chaoshan of Guangdong Province was finally closed down," Zheng said in a recent interview with the state-run China Daily newspaper. A private investigator for nearly seven years, he picked up his investigation techniques from his years as an official with the local anti-corruption bureau.
"A career as a private investigator is like no other," says Zheng. "Every day is an adventure, with new challenges to meet and new problems to solve."