SAN FRANCISCO (CBS SF) — Of the 220 licensed massage establishments in San Francisco, over a third were found to have active online listings advertising erotic services, according to the Human Trafficking in San Francisco Report 2016 (PDF).

But erotic services, including prostitution and solicitation of prostitution remain illegal in San Francisco and across California.

The recently released report states that nearly 500 cases of human trafficking were reported in the city in 2015. 122 of those cases involved minors and 270 of the cases were identified as sex trafficking cases.

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Regarding massage parlors, the report notes that not all of the massage businesses advertising online are necessarily involved in human trafficking, but that San Francisco Department of Public Health inspections at massage parlors in the city reveal indicators of human trafficking. Those indicators include locked doors and illegal, on-premise living quarters. The report also notes that locked business doors could be indicators of commercial sex activity and not necessarily human trafficking.

Upon going to Backpage.com, a website known for advertising erotic services, many massage businesses in the city were indeed advertising on the site.

Last month, Backpage.com’s CEO Carl Ferrer was arrested on a California warrant in Texas following allegations that sex trafficking victims were being forced into prostitution via ads posted on his website.

In San Francisco alone, there were 47 listings posted on Friday to Backpage.com’s massage page advertising “sensual” massages and photos of scantily-clad women.

Many of the San Francisco massage businesses advertised on Backpage.com posted phone numbers and addresses on their Backpage.com listing, making them easy to locate.

Two, the Asian Palace Spa and the Thailand Spa, are located on Kearny Street.

Despite advertising on Backpage.com that walk-ins were welcome, female employees at both businesses — both open for business and with no visible clients — maintained that no one was available to give a massage to a potential female customer on Friday afternoon.

Employees at both businesses refused to schedule appointments and discouraged waiting around for the next open appointment.

Both businesses had front doors locked to the public that required the customer to ring a bell for entry and both had multiple surveillance cameras aimed at the doorway.

Thailand Spa advertised on Backpage.com that they are open seven days a week “10 a.m.-Late Night” while Asian Palace Spa advertises “Hot Asian Action”, “Beautiful & friendly Asian staff” and the “Best & Hottest In SF!!”

In 2015, the San Francisco Department of Public Health reported conducting 563 inspections of massage parlors and issued 500 violations.

While the majority of violations were regarding unsanitary conditions (212) and unlicensed practitioners (134), there were 53 for prohibited living quarters and 31 for locked doors posing a safety hazard.

No human trafficking arrests were made as a result of the 2015 inspections, but 12 massage establishments in the city did receive suspensions. One of those suspensions was for illegal/lewd acts, another was for having residential sleeping areas at the facility and four were for operating after 10 p.m. and/or having locked doors. The report doesn’t name the establishments suspended or cited.

The San Francisco police department’s Special Victims Unit participated in 35 massage establishment inspections last year, according to the human trafficking report. However, the report doesn’t note whether any non-human trafficking arrests were made during those inspections.

Other San Francisco massage businesses with listings on Backpage.com include one at 928 Sutter St. advertising “come see new young beautiful girl” and the “youngest lineup in San Francisco.”

According to the Department of Public Health, the department revoked 73 permits at massage businesses from 2008 to 2012, but that 45 of those establishments simply reopened under a different business license.

On Backpage.com, many of the massage businesses maintain they’re celebrating their grand reopening with new management and “new girls.”

By Hannah Albarazi – Follow her on Twitter: @hannahalbarazi