WILLIAMSBURG, BROOKLYN — The black market for illegal Airbnb listings is thriving in northern Brooklyn despite the city's attempts to curtail it, according to a new report.

Former NYPD officer Herman Weisberg investigated Airbnb hosts in the room-share site's three most popular Brooklyn neighborhoods — Williamsburg, Bushwick, and Bed-Stuy — and found business is booming, the New York Post reported Sunday. Weisberg, who went undercover for the Hotel Association of New York, said illegal subletters are remaining under the radar by telling guests not to tell anyone they're staying in an Airbnb.

"Hosts are engaging deceptive practices to avoid exposure and to hide from Airbnb's image problem," Weisberg told the Post. "They're putting emphasis with anonymity." Some listers are even hiring management companies keep on top of their numerous rentals, according to the investigator.

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Weisberg's findings come in the wake of a crackdown on illegal Airbnbs by the Office of Special Enforcement, whose officers issued 32 percent more violations in the first half of 2017 than in the same time span in 2016.

But Airbnb supporters worry listers who do obey New York City strict laws — which mandate Airbnb listers occupy the apartment with rental rooms or face up to a $7,500 fine — are being punished along with the guilty.

Several Airbnb listers in Brooklyn told Quartz that Office of Special Enforcement officers had issued them unmerited building code violations when denied access into Airbnb users' homes. Airbnb spokesperson Josh Meltzer argued that the hotel lobby's study had similarly targeted lawful listers when they hired an undercover investigator.