Every two months, Valentina visits about 30 men enrolled in San Francisco's "john school" to tell them a sex story they don't want to hear.

The men are part of the city's First Offender Prostitution Program because they've been arrested for soliciting a prostitute, usually in the Mission or Tenderloin. If they agree to pay a $1,000 fee and spend a Saturday afternoon listening to sex-trafficking experts, neighborhood activists and doctors who subject them to photographs of venereal diseases, the district attorney's office will drop the misdemeanor charge.

Valentina, a striking Russian woman with jet-black hair (to protect her privacy, her full name is not given in this article), explains how she was molested from age 8 to 13 by a cousin; how she was a full-blown alcoholic and heroin addict at 21; how she became an "escort" a year later, and by age 25 was working Mission Street.

She hated every interaction with every client.

"Sometimes I see it register on their faces," said Valentina, 37, a mother and San Francisco resident who's been off the streets and sober for 10 years. "The fantasy isn't what they thought. ... I don't get much feedback from them. I do my presentation and go about my day."

Yet Valentina's presentation as well as the other components of john school are effective, according to a study to be released in the coming weeks by the U.S. Department of Justice. In the largest study of its kind, researchers concluded that men who attended San Francisco's john school were 30 percent less likely to be rearrested for soliciting a prostitute than men who did not attend such a program.

Researchers compared data collected from 5,000 johns who completed the daylong class in San Francisco over the past 12 years with roughly 75,000 men arrested for soliciting prostitutes in California who did not attend john schools. The costs of the school are covered by the men's fees, according to the district attorney's office.

"The punch line is, these programs work," said Michael Shively, a criminologist at Abt Associates, a Massachusetts-based research firm and the primary author of the two-year study commissioned by the National Institute of Justice. "Some men are probably responding to the appeal of their own self interests, which in the class emphasizes the personal risk they face if they continue to involve themselves in prostitution. And some men may be responding to the information conveyed about the harm they are causing the women they hire, and to the communities where the prostitution takes place."

The study arrives at the same time Supervisor Jake McGoldrick asked for an audit of the city's program, wondering if the arrests are worthwhile and the money for the program is being well spent. He did not respond to messages seeking comment for this story.

When the First Offender Prostitution Program began in 1996, it was considered a noble experiment in a progressive city. Since then, 39 cities have modeled programs after San Francisco's.

The class was co-founded by Norma Hotaling, a former street prostitute arrested 30 times before she gained sobriety and started Standing Against Global Exploitation, a San Francisco group committed to ending commercial sexual traffic.

Hotaling said a San Francisco police officer who repeatedly arrested her was the first to suggest that her johns needed an education instead of jail time. Hotaling recalled the advice and later developed the curriculum, which includes a six-hour course featuring multiple speakers who explain the negative impact prostitution has on women, their clients and the communities where it thrives.

More recently, Hotaling said, presentations have focused on global sex trafficking, to help men consider their role in the illegal phenomenon.

"The men who seek out prostitutes don't like to think they're part of exploiting someone," Hotaling said. "They like to believe it's a victimless crime."

Since the program's inception, critics have wondered if the classes had any real impact on the men and the streets, Hotaling said. Previous studies have shown that recidivism rates among men arrested for soliciting prostitutes is particularly low compared to other crimes, such as robbery.

Shively, the study's author, said in San Francisco the recidivism rate for such men was about 8 percent before the program began. Now, it rests at about 5 percent.

"It's a significant drop if you consider it didn't have much further to go," Shively said. "The results are surprising."

Anecdotally, the researchers also found that police departments reported street prostitution declined in the cities where the classes were available. Shively said the study could not factor what role online prostitution may have played in reducing street prostitution in the past 12 years.

"But for some people, it's good enough that street prostitution is out of their faces and behind closed doors," Shively said, "where the entire community doesn't have to deal with it."

Robert Garcia, a member of Save Our Streets Tenants and Merchants Association in Lower Nob Hill, credits the john school program as helping to reduce street prostitution in his neighborhood near Post and Hyde streets. As part of the agreement between Hotaling's organization, which facilitates the school, and the district attorney's office, which agrees to drop the charges, the Police Department is required to run eight sting operations per month designed to arrest the johns. Last year, the department arrested 335 men, up from 130 in 2006.

Garcia has monitored the Post and Hyde intersection near his home for about 20 years, and said he was skeptical the program would have any impact.

"This place used to be infested with prostitutes," Garcia said. "But we don't see as many hanging out on the corners, and we don't have as many cars circling the blocks, whistling and all that."

Hotaling said the study's results validate the once-experimental school, and hopes the city will expand the program.

"It doesn't matter if they get picked up on the streets or through a new Web site that's popped up," Hotaling said. "There's always a need for the education."

Learn more

For more information about Standing Against Global Exploitation, the nonprofit that facilitates the First Offender Prostitution Program with the S.F. Police Department and district attorney's office, go to: www.sagesf.org.