But Courtney Kanagi, an outreach worker, has learned how to decode bits of urban detritus that most people ignore. She knows what these signs mean: the crawl space beneath the stairs was someone's home.
So Kanagi climbed out of her van and, after a few minutes of poking through the bushes, found a woman sound asleep with a white sheet drawn across her face.
Los Angeles County has more homeless people -- estimated at roughly 73,000 on any given night -- than any other metropolis in the country. It also has a topography in which dense urban areas frequently brush up against tiny pockets of wilderness.
For those without houses, this landscape offers many opportunities for ingenious solutions -- aeries beneath bridges, riverbed encampments, ad hoc tree houses with million-dollar views -- to the problem of where to sleep.
Kanagi and her co-workers at the nonprofit People Assisting the Homeless have become experts in the creativity and resourcefulness of homeless architecture, in the surprising and heartbreaking ways that thousands of people -- up to three-quarters of them suffering from mental illness or physical disabilities -- manage each evening to protect themselves from the elements and from predators and tuck into bed, often in plain sight.
Spend some time with Kanagi and you'll never look at the city's hidden corners the same way again.
To understand the scope of homeless architecture in Los Angeles, it helps to begin with some numbers:
Fewer than 20% of the region's homeless can be accommodated in shelter beds on any given night.
About one-third of them, including thousands of families with children, retreat to motel rooms, basements, garages and parked cars, according to the Los Angeles Homeless Services Authority's 2007 census of homeless.
That leaves tens of thousands of people sleeping outdoors, at the mercy of the elements.
Their options are stark:
* They can hunch in groups on the sidewalk or in alleys behind dumpsters, putting up with disturbances because of the promise of safety in numbers.
* They can find a hidden stairwell or doorway, abandoned building or freeway underpass.
* They can venture into the brush and make their own living spaces, or encampments.
"Nobody can know what it is like until they've lived one night. One night out here," said a woman who lives with her dog beneath a bridge in the San Gabriel River watershed.
The woman, who did not want her name or exact location printed, had set up camp between a concrete bridge support and a chain-link fence on a little ledge above a bike path. She and her husband had created sleeping quarters and a makeshift office, with a mug full of pens and a stack of library books on supernatural events that the woman said she liked to read because they give her comfort.
But she warned that no one should romanticize her situation. Her little abode next to the riverbed might seem out of the way and even peaceful, especially when morning sun etches the landscape with gold. But the woman, who is 34 but is missing teeth and looks much older, said she lives with pressing fear that police will force her to move or that gang members will menace her. And it's frequently cold at night.
She said she used to live in an encampment in Hollywood that she protected with a system of battery-operated baby monitors that served as mobile burglar alarms. But she left a year ago because she came to believe it was too dangerous.
The largest concentration of homeless people in the L.A. region can be found on the streets of downtown's skid row, but the homeless live in almost every community. Some of their encampments are elaborate -- and occasionally arresting in terms of the amenities they afford.
Rudy Salinas, who is in charge of outreach for PATH, recalled an encampment he encountered a few years ago under a bridge in the San Gabriel River watershed that featured a working whirlpool bath. It was powered by electricity spliced illegally from a nearby power line. The men living there had obtained the spa after it fell off a truck on the 10 Freeway; they carried in water to fill it.
Housing solutions are no less imaginative in the city's urban core.
Scores of homeless people have built semi-permanent homes in the chaparral-covered hills that rise above the Hollywood Bowl; hundreds more, including some immigrant families, live in Griffith Park and Elysian Park and on islands in the Los Angeles River.
A man known as the Godfather lived in the scrub above the Cahuenga Pass for at least seven years.
The Vietnam veteran dug his "house" into the side of a hill, with a seating area fashioned with wooden planks where he would take in the scene with his dogs, outreach workers said. (Vietnam veterans are known for constructing impressive encampments. In some of them, "you feel like you're in someone's apartment," Salinas said, adding that some vets have said they learned how to build them while in the service.)
The Godfather had to move about a year ago after officials, concerned about fire danger, bulldozed the area. He's lately been seen on the streets of Hollywood.
In a region defined by its freeways, it should come as no surprise that many homeless people have turned to the steel and concrete behemoths for shelter.
A few years ago, homeless people were discovered living above a concrete channel for runoff along the 405 Freeway in Long Beach; they had protected themselves by setting up a system of informal checkpoints.
Police and outreach workers have also discovered people living inside the supports of the Hollywood Freeway.
Earlier this summer, city workers found a man living 20 feet in the air in a nest-like house tucked into the supports of the 1st Street bridge. Nearby office workers said he had been there a year or more.
Sam Davis, an architect who specializes in building shelters for the homeless, said he was not surprised by the ingenuity and complexity of the structures. "Everybody has a nesting impulse. It's the human instinct," he said.
Advocates say they're not sure why some folks prefer to sleep in remote places by themselves while others group together in places like skid row or Hollywood.
Shannon Legere, homeless assistance program director at the Mental Health America Village in Long Beach, speculated that people with severe mental illness, including those with schizophrenia, might gravitate toward isolated spots because they can't tolerate being around crowds and they feel safer by themselves.
Some people alternate between crowded streets and remote camping.
Paul Driscoll, 54, said he prefers the peace of Griffith Park but sometimes sleeps alongside many others on a side street off Hollywood Boulevard so he can be available for jobs early in the morning.
On a recent night, Driscoll, who takes care to shave every morning, had unfolded a flattened cardboard box onto the sidewalk and layered two blankets on top for warmth and padding.
Then he settled down with his battery-operated black and white television to watch "NCIS." He used headphones, because there were so many people sleeping near him.
"Mi casa es su casa," he said with a smile before turning his attention to the TV.
One fact about being homeless: It can mean moving a lot.
Isa Ali, 33, waited at a food line and reminisced about the various places he has stayed over months of being without permanent shelter in Hollywood.
One favorite was an empty house with comfortable pool furniture.
Ali, who said he moved to Los Angeles from New York because he wants to be a screenwriter, slept beside that pool for days, storing his possessions under pool cushions during the day, until the owner discovered him and told him to get out. He also spent some time at a multimillion-dollar house in the Hollywood Hills that was vacant while it was for sale, he said.
More recently, Ali said, he moved to the roof of an apartment building. The site pleases him, he said. There is an impressive view of city lights, and there are also several nearby billboards, which Ali regards as his "posters."
Another man, who gave his name as John, interrupted. To survive on the streets, he said, it is necessary to live by "a different set of rules."
"Where would you sleep if you were homeless?" he asked.