A cash-rich crowd on the prowl for fun, neighbours who choose to turn a blind eye and slack policing — the bed is made for the bar-sex racket to thrive in town.

Be it Salt Lake or south Calcutta, the trend is taking root in the country’s “culture capital”.

It is very difficult to crack down on a racket operating from bars, admits a senior officer of Calcutta Police’s law section.

“If two adults meet in a bar to fix a rendezvous, you can’t haul up the owner of the bar,” he reasons.

For any bar to operate, there must a clearance from the law section, besides the customary no-objection certificate and registration from different departments, including excise, and the relevant civic body.

“The problem of raiding a place often lies with the credibility of the complainant. For genuine operators, at times a single raid may be enough to cast a cloud over the place,” explained an officer of the detective department.

The raids, nevertheless, are carried out at regular intervals. The last big one was in a parlour in Posta, when a clutch of clients — all youths from well-to-do families — were caught red-handed. The local police claimed ignorance about the racket being run under their noses.

“Those involved are often from the higher strata of society. The racket operates on a word-of-mouth basis and unless there is a specific tip-off, it’s tough to crack,” admitted Subrata Ghosh of Shakespeare Sarani police station.

But the sleaze epicentre has shifted from the infamous Park Street-Free School Street-Rafi Ahmed Kidwai Road belt to the emerging pockets of Rashbehari Avenue-Southern Avenue in the south and Kankurgachi-Narkeldanga in the north.

“The activities around Park Street, in particular, have nearly stopped (after a series of raids),” claimed Faiz Ahmed Khan, officer-in-charge of Park Street police station.

Deputy commissioner of police (south) Anuj Sharma insisted that anti-sleaze vigil must be intensified.

“I have specifically asked my officers to watch certain addresses very closely and pick up all information possible about such activities,” said Sharma.

But the one thing that cops crib about is the lack of “community policing”, with local residents “least bothered” about what’s happening next door.