(Neither of these people are mentioned in this story.) Pedro Ribeiro Simões / Flickr, CC A small number of Airbnb customers appear to be using the service for hookups.

Airbnb is unlikely to endorse such behaviour, but some users told Business Insider they had slept with people or been hit on as a result of transactions that were facilitated through its platform.

Founded in 2008, the San Francisco-based company has an app and website that lets people rent out their rooms and properties for short stays to travellers in return for a 3% commission. The firm, which has helped thousands of homeowners supplement their income, encourages users to set a profile photo so people can see whom they're about to stay with.

Airbnb rentals are often separate, wholly contained properties — like a flat or house where the guest stays alone. But many are simply rooms within the owner's home. You're essentially going to a stranger's house and sleeping in a stranger's bed. It's supposed to be a purely financial transaction.

But sometimes one thing leads to another.

One 25-year-old Airbnb host named Stuart told Business Insider he had sex with a 36-year-old Brazilian woman in July as a result of a booking that was made via Airbnb.

Stuart, who does not wish to reveal his surname but was able to confirm he lives in London and works as an architect, said: "I asked if she would want to come to my bedroom. She did, and we had amazing sex. Mind-blowing. She tiptoed back up to the other bedroom during the night and nobody noticed. This then continued every night for the rest of the week, and we slept together every night."

Mary, another Airbnb user, told Business Insider about her "one-night stand" that occurred somewhere in England last year.

"It happened last Easter," she said. "Me and two of my friends decided to spend the weekend on the coast to practice surfing. I was in charge of booking the place for us. I was not expecting our host to be a serious silver fox: a proper surfer dude in his early 40s, no kid, no wife, full of good vibes.

"We shared a beer and had good conversations with him the first day. The next day we invited him for a drink in the evening. We were all quite drunk, and my friends joked about the fact that he was interested in me. They left the pub to leave me alone with him. We came back home later in the night and shared a bottle of wine in his flat. Then he kissed me and we went to his bedroom to spend the rest of the night. We left the morning after. We kept in touch only for a very short time after that ... It was totally unexpected, but fun."

Another Airbnb host, this time in America, told Business Insider over Airbnb's messaging platform that the thought of finding a girlfriend or a hookup through Airbnb had "crossed his mind." The male host is thought to be in his 50s or 60s.

A different host, also in America, said: "I can see how men could choose looks over reviews. For now I am relying on the organic universe's pick for me, and it is working out."

Yes, there is a thread on Reddit for it

One of Airbnb's listings. https://www.airbnb.com/rooms/5704246 Numerous people online have claimed to have had sex with their guests. A thread on Reddit this summer invited people to talk about this very topic.

The self-described Airbnb host who started the thread said his roommates had slept with two of their Airbnb guests.

"Once after the guest had checked out, but returned for a party we were throwing," wrote the thread's creator, who goes by the username "airbnbsex."

"The other time during their short stay — the guest left promptly the next day."

Business Insider contacted the user to confirm but did not hear back.

Reddit user "bayek" added: "I'm sure it happens relatively often, but my guess is that if you make it your goal to rent out your place solely for hooking up, Airbnb might have a few questions."

Airbnbsex replied: "Definitely not the goal, but yeah I imagine it happens frequently. I kinda wish Airbnb would give us some visibility on their policy regarding it."

Not everyone on the thread shared the same outlook. Reddit user "YourCardinalRule" wrote: "This is just a horrible idea. If these guests complain about that s--- to Airbnb you could be in for a world of hurt."

Over on the question-and-answer website Quora, someone posed the question: "Has any airbnb hosts had sex with their guests?"

Mark Wagner, a Quora user who describes himself as a supporter of Web 2.0 and the new economy, replied: "Yes, both as a host and as a guest. But don't get the wrong idea about the site, it is very professional."

Sam Berko, another Quora user who has not filled out his profile, simply wrote: "Yup."

Business Insider contacted Wagner and Sam to confirm these incidents but did not hear back.

Overstepping the line

The vast majority of the sexual encounters occurring over Airbnb appear to be fun and consensual, but a small number of incidents suggest the platform may be being exploited by the occasional host.

Sophie Dand, a teacher who has used Airbnb, told Business Insider that her male host in Hvar, Croatia, cancelled a booking he had agreed to with a family when he found out that Dand and her three female friends in their 20s wanted to stay with him.

Airbnb guest Susy Anese. Susy Anese

Airbnb allows guests and hosts to leave reviews for each other. This deters the vast majority of users from behaving inappropriately or committing crimes — they will be kicked off the platform if they get too many bad reviews.

The company also has a 24/7 customer-experience team that is available to talk to Airbnb users who find themselves in trouble.

'I literally had to run away from my host in Paris.'

Last December, however, a 34-year-old man was sentenced to 12 years in prison for raping two Americans on holiday who rented his Barcelona flat through Airbnb. And a man from Massachusetts named Jacob Lopez said he was raped in Madrid this July, according to reports.

Regarding Lopez's accusations, Airbnb told The Independent: "While the issue of sexual assault is a global challenge — and different laws in different countries impact what a web platform can do to help — there is nothing more important to us than the safety of our community."

Airbnb user Susy Anese, an Italian who lives in London, told Business Insider: "I literally had to run away from my host in Paris and report him.

"The guy got weird from the beginning, as he had already rented out the room so he offered me his room and he slept on the sofa," said Anese, who was visiting some friends in the city but had organised her own accommodation.

"He kept trying to hug and kiss me and saying he didn't want me to leave. He lie down with me Saturday night while I was trying to sleep. I got seriously afraid but I didn't want to say anything as I was scared about his reaction. The worst was on Sunday morning when I woke up and he was staring at me. Airbnb customer services sent this reply to a guest who said she was sexually harassed by an Airbnb host. Susy Anese

"As soon as he left, I packed and ran away. I contacted Airbnb, and at the end they said it was my word against his so they couldn't do anything except send me a coupon as a refund for the last night I didn't spend there. I had to send a couple of emails to get it."

Anese added: "It was awkward and not very nice at all. I told them they should investigate, as it's not nice for a girl that's travelling alone to be in this kind of situation."

Airbnb contacted Anese and offered her a full refund after we told the company we had learned about the incident.

Airbnb's response

Airbnb said, "Our initial response to this inquiry was unacceptable. We've apologised to this guest, issued a refund when this matter was first reported, and are providing them with our full support. We have also suspended this host while we investigate further."

The company declined to comment further but our understanding is that the company clearly believes that close encounters conducted via Airbnb are relatively rare and that the company does not condone this type of behaviour.

Business Insider was also able to talk to an Airbnb manager at a London tech event last month. Sofia Gkiousou, public-policy manager at Airbnb, told Business Insider at a conference on the so-called sharing economy that Airbnb worked very hard to ensure trust was developed between the host and the guest.

"We're trying to ensure that people feel safe in sharing their space, but guests also feel safe in going to that space," she said. "The level of engagement those two people want to have is obviously up to them. We listen to the community all the time so if there are improvements needed in the product or how the relationship works or the level of trust then we look into them."

Some 50 million people across 190 countries have used Airbnb, which was valued at $25.5 billion (£16.6 billion) in June.

Debbie Wosskow, founder of Love Home Swap and chair of Sharing Economy UK, which counts Airbnb as a member, said last month that she wanted to develop a "trust mark" for the sharing economy.

"The big meta question is how can we trust people to stay in our homes?" she said at the same sharing economy conference that Airbnb spoke at. "Do we know that the peer ratings on our system are enough? What is it that the industry coming together can layer on top of that?

"We have undertaken a piece of work to develop a trust law in the sharing economy," Wosskow said. "We're partnering with Oxford University, who taught the first academic course on the sharing economy last term.

"That trust mark will be in a form that can be piloted by operators in the sharing economy. It will allow sharing-economy companies to display some kind of universal stamp that says this is a responsible platform and this is trusted."

Some names in this story have been changed to ensure sources aren't identifiable.