A court sentenced seven staff members and the owner of a shady Houhai bar to prison terms of at least a year for inflating the bills of customers and threatening to beat them if they refused to pay.

Xicheng district court ruled that between July 4 and October 29 last year, the bar Blue Eyes used a number of dirty tricks to fleece 32 customers out 300,000 yuan ($48,000), a court spokesman said Monday.

The conviction is the latest in a cat-and-mouse game between police and so-called "black" bars that are periodically shut down during police crackdowns then just as quickly reappear when the heat is off, said Wu Meibao, the director of the management office of the Shichahai community committee, located in the Houhai area.

Touts and bar owners become so familiar with the faces of local undercover police that reinforcements must be borrowed from other districts so they will not be recognized, said Wu.

Some other local bars, usually those that are struggling financially, also use the same tricks as the Blue Eyes staff, he said.

Often, a beautiful young woman will lure customers into a bar, and persuade them to buy her drinks. Recently, handsome young men started doing the same thing, he noted.

Some touts also serve as prostitutes or pimps, but services are provided at a separate location, not the bars.

Wu said some bars use two menus. "One menu has reasonable prices and is provided when clients order. The other, with higher prices, is presented when customers pay the bill," said Wu.

Bar staff will also sneak empty bottles onto the customer's tables and include them in the final tally. Sometimes the staff inflates prices on the bill by adding a service fee. Muscular doormen nicknamed "groundskeepers" threaten to rough up customers who balk at the inflated bills, said Wu.

The lowest sentence handed to a Blue Eyes staff member was one year and two months, and the longest was three years. A ninth person surnamed Nie, the co-owner of the bar, is still at large and was not sentenced.