San Francisco's Folsom Street Fair, the sexually explicit celebration of bondage and leather now in its 30th year, has shaken off its kinky image, attracting mainstream corporate sponsorship from the likes of Marriott Marquis Hotel and American Airlines.

"It's a great, local, San Francisco-based homegrown event, so it's exciting for the San Francisco Marriott Marquis to be part of it," said Frank Manchen, director of sales and marketing for the hotel.

The LGBT market is "a diverse community with many different options" when it comes to travel, he said. "I don't think it's anything new that corporate America is figuring out how to woo those dollars."

Still, the role of the Marriott chain in San Francisco's most graphic public festival, set for South of Market on Sunday, raises eyebrows of some longtime political observers.

Marriott International Corp., founded by magnate J.W. Marriott, is still managed by the politically active Marriott family. They, like board member and 2012 GOP presidential candidate Mitt Romney, are devout members of the Church of Jesus Christ of Latter-day Saints.

The Mormon church publicly supported Proposition 8, and its members contributed more than $20 million to the passage of the 2008 anti-gay-marriage initiative, which has since been overturned by the courts.

Yet the San Francisco Marriott is a "proud sponsor" of the annual clothing-optional fair, described by organizers as "400,000 of your closest, kinky friends spread out over 13 city blocks of adult entertainment ... for an 'only in San Francisco' experience."

It includes more than 200 booths selling fetish gear and toys, "public play stations," erotic artists' areas, and "more eye candy than you can shake your (private parts) at," the event website says.

Indeed, mobs of leather-clad kink-lovers from around the globe converge in the South of Market neighborhood annually for the event, spending millions and raising an estimated $625,000 for charity this year.

Mutual attraction

"In the case of Marriott, they've been very supportive of us," said Folsom Street Fair executive director Demetri Moshoyannis, who notes that a third of the visitors come from outside the city. "They understand that our folks are wanting hotels - and are willing to pay for them."

While most of the fair's sponsors are still adult-oriented businesses, the increasingly high-profile role of major corporate backers like Marriott, American Airlines and the tony Kimpton restaurant and hotel chain in a proudly offbeat sex fest underscores the burgeoning buying power and political clout of the fair's participants.

"Corporate America is scrambling to do what it can to support LGBT travel, organizations and charities," said Fred Karger, who ran as an openly gay Republican presidential candidate in 2012. "It's a complete reversal from the days where people were petrified - and even gays were petrified," to be associated with risque events.

The Mormon Church was "so notoriously identified with Prop. 8," that there were calls for a boycott of the hotel chain - which still stocks the Book of Mormon along with the Bible in its hotel rooms - by LGBT leaders around the country, Karger said.

Marriott's executive chairman and chairman of the board, Bill Marriott, posted a statement on his website stressing that "neither I, nor the company, contributed to the campaign to pass Prop. 8," Karger said, adding that the firm has consistently stressed through its actions that it was "built on basic principles of respect and inclusion."

Terry Connolly, dean of the Ageno School of Business at Golden Gate University, said Marriott's sponsorship in San Francisco helps to allay concerns that it is hostile to the LGBT community.

"Marriott doesn't want to be singularly identified with antipathy to the gay movement, and this is one way of sending a message to a community where it might be well received," he said.

And there's less chance of a downside in an era in which the erotic trilogy "Fifty Shades of Grey" has been a best-seller, Connolly said.

"The younger generation is way more libertarian and antihypocritical than previous generations," he said. What was once seen as over the top is to Millennial consumers "all in fun," he said. "That's how it's viewed."

More subdued

Adult entertainment businessmen like Tim Valenti, CEO of San Francisco's Naked Sword, a leading gay porn website, said major corporate involvement has had the effect of toning down the festival.

These days, "it's a huge event" that attracts fetishists, but also lots of "bridge and tunnel" people - East Bay surburbanites - and parents with babies, Valenti said. "I never saw that years ago."

It also means Folsom is a much more mainstream affair, he said.

"In the old days, what made the fair so dirty was that all the vendors were part of the act; they were the act," Valenti said. While public sex, nudity and bondage displays are still common, organizers have "come down with an iron fist" on sexual activity in booths of the vendors, he said.

The Marriott Marquis' fair involvement, which has included corporate backing for three years, now also involves sponsorship of Up Your Alley, a July Folsom Street Fair offshoot that promises: "You won't find a filthier event here in the states," the event website says.

Manchen acknowledged that involvement in a major charity drive involving so many events and tourists may bring controversy. But, he said, it is "the right thing to do" to be a good neighbor in a diverse community like San Francisco.

"It's fun to be a part of it," he said. "Anyone who's interested in people, and watching people - it doesn't get any better than that."