San Franciscans know everything about homelessness — just ask them.

But according to nonprofit providers and city officials who work with the homeless every day and have interacted with thousands of homeless people in their careers, a lot of conventional wisdom about one of San Francisco’s most stubborn problems is pure myth.

That’s OK. I don’t understand everything about this city either. Like how in the world we have a $9 billion budget but the streets remain riddled with potholes. Or the point of all those apps being made by our tech companies. Or our weather.

Here are some of the most common myths about homelessness in the city. And, like a really depressing episode of “MythBusters,” some answers as to whether they’re legit.

Myth 1: Homeless people flock here from elsewhere because of San Francisco’s generous services. If we just cut the services, the homeless problem would disappear.

My email inbox would be about half as full if this myth weren’t out there. Everybody seems to take it as fact. But are we the “Field of Dreams” for homeless people? Not really.

The most recent homeless count, conducted in January 2015, found 6,686 homeless people in the city. Seventy-one percent of people reported living in San Francisco when they became homeless, up from 61 percent in 2013. Just 10 percent said they were living outside California when they became homeless, and the remaining 19 percent were living in the state but not in the city.

Of those who came from outside San Francisco, 22 percent said it was for homeless services and benefits. So a few hundred of the 6,686 homeless people in San Francisco came for our great homeless services — a sizable chunk, but nowhere near the majority.

Other reasons for moving to San Francisco cited in the homeless count were that they were looking for work, that they sought acceptance in the gay community, that they were traveling through, or that family and friends are here. In other words, the same reasons many of us came to San Francisco.

“I think it’s a very rare occurrence that somebody who’s struggling Googles ‘homeless services’ and comes to us for them,” said Sherilyn Adams, executive director of Larkin Street Youth, which works with homeless teens and young adults.

That doesn’t mean that everybody who came here and wound up homeless had the best-laid plans, but advocates say it’s harder and harder to arrive in San Francisco looking for your shot and to actually make it.

Matthew Doherty, executive director of the United States Interagency Council on Homelessness, came to San Francisco recently and said just about every city he visits claims it’s a magnet for homeless people because of its robust services. Los Angeles, Seattle, Portland, Ore. — you name it.

If every city says it, perhaps there’s nothing all that special about San Francisco. There can only be one “Field of Dreams,” right?

Myth 2: A lot of people just want to be homeless — it’s a lifestyle.

Yes, a lot of homeless people refuse services — at least at first. But Jackie Jenks, executive director of Hospitality House, which runs a shelter and offers other homeless services, says there’s more to the rejection than just wanting a life on the streets.

“A lot of times people have been traumatized and re-traumatized and they don’t think it’s going to happen anyway,” she said of getting help finding a better life. “They might need a little bit more work in order to be able to make that leap.”

Sam Dodge, Mayor Ed Lee’s coordinator of homeless services, said many people have had such awful experiences in their lives, they’ve put up a huge wall for self-protection.

“It can be a psychological strength to say ‘no’ and stand up for yourself,” he said. “They’d rather stand on their own two feet than live on their knees.”

But this often melts away when the services come with less rigidity. People often turn down the traditional shelter because it comes with a curfew, a lot of bureaucracy, and a prohibition on partners and pets.

The year-old Navigation Center on Mission Street doesn’t have those rules, and homeless people are much more likely to accept beds there. The shelter at Pier 80, which also has more relaxed rules, now has 180 beds and is close to capacity each night.

Dodge said that in his entire career, he’s met only three or four people who really do want to spend their lives on the streets.

Myth 3: The shelter system has plenty of beds for any homeless people who want them.

This myth is perpetuated by city officials, probably to prove they don’t need to fund more shelters. But Jenks says it’s not true. The shelter system has 1,200 beds, so common sense would say that it’s not enough to support a population of almost 7,000.

The city’s www.sf311.org website tracks people on a waiting list for a shelter bed, and last week the tally was 698 people. “That shows us people do actually want to get into shelter,” Jenks said.

Most nights, it’s true that not all of the 1,200 beds are occupied. But that’s usually because someone didn’t show up to claim a bed they were granted or because of some other technicality, Jenks said.

Dodge said there are often a few dozen vacant shelter beds per night, but added, “There’s a tremendous demand for shelter.” Maybe something in the allotment of shelter beds needs fixing.

Myth 4: If we solve homelessness, all of our quality of life issues on the streets will disappear, too.

Dodge’s biggest gripe when it comes to myths about homelessness is that homeless people are blamed for all the discarded needles, feces and puddles of urine littering our sidewalks. In a Venn diagram, there would obviously be a lot of overlap, but they’re not the same issue.

The Department of Public Health estimates there are about 20,000 intravenous drug users in the city. So even if every homeless person was one, which they’re not, there would still be more than 13,000 housed people shooting up in the city. City officials say some intravenous drug users who have housing choose to shoot up outside so if they overdose, passersby will notice and help.

Dodge added that the Department of Public Works responds to a lot of requests for steam-cleaning feces and urine that aren’t related to homelessness.

“The big pee spots are near bars and late-night drinking,” he said. “Homeless people aren’t the only people who are peeing on the streets.”

And of the “the S.F. poop maps,” as Dodge put it? “A lot of that is not just human feces — it’s also dogs,” he said.

We believe this is the first time in Chronicle history that “big pee spots” and “poop maps” were uttered by a city official and appeared in the same column.

And with that, we’ll await your emails and tweets telling us the experts are wrong, and the myths are true. Ready, set, go!

Heather Knight is a San Francisco Chronicle staff writer who covers City Hall politics. Email: hknight@sfchronicle.com Twitter: @hknightsf