"Any time we have large numbers of people in town, [the escort] business is probably going to jump," said Lt. Rick Ryan.
And the film festival is, by far, Park City's biggest event of the year, drawing people from around the globe.
During the 2006 film fest, police triggered three sting operations after calling escort services.
Those operations led to seven arrests for "sex for hire," which is a class A misdeĀmeanor.
Park City police have never launched an escort sting without making a bust.
"We have a 100 percent arrest rate," Ryan said. "For the most part, this is a front for prostitution."
Business licenses cost $47. City officials hope the new law will help police keep tabs on female escorts and their male drivers who are based in Salt Lake Valley but have Park City telephone listings and, in some cases, phony Main Street Park City addresses.
Before the ordinance was updated, 21 escort services had obtained business licences.
Since last month's amendment, no individual escorts or drivers have applied. But officials know they haven't simply cleared out of town.
Conducting business in Park City without a license is a class B misdemeanor.
Those answering telephone calls at the Park City listings for Blondes & Brunettes, as well as First Class Escorts, refused to be identified and had no comment.
Concerns surrounding escort services go beyond sex-for-hire, Ryan said. Prostitution brings many other crimes with it: drugs, guns, assault, theft and even the human sex-slave trade.
During an escort sting last summer, Ryan said police arrested a woman who was an undocumented immigrant from Mexico. She later told authorities she was working off a debt to those who smuggled her into the country.
Prostitution is not something tourists might identify as they stroll down Park City's Historic Main Street or while sunning themselves on the deck at Deer Valley's Silver Lake Lodge, said Mayor Dana Williams.
Nonetheless, the perceived increase in the trade does not mesh well with Park City's marketing push as a family-friendly vacation destination.
"This is not the image Park City wants to portray," the mayor said. "The prostitution, drugs and guns. All those things made us very nervous."