FOR THOUSANDS OF people in San Francisco, single-room-occupancy hotels are the last stop before homelessness. For some, like Vance Maxwell Elliot and Bernhard Calloway, the SRO life is suitable. But for most, like John and Linda, things couldn't get much worse.

Elliot is a 73-year-old Korean War veteran, living on his $800 a month Veterans Assistance check for his psychological disability since the war. He said he was a classmate of Daniel Ellsberg's at Harvard University before receiving his master's degree in sociology from UC Berkeley. Since then he's been in and out of mental institutions. A year ago, Elliot said, he decided to pick up a heroin habit.

I wondered why someone would get into smack at age 72, at least until I visited him in his room at the Aranda Hotel on Turk Street (arguably the worst SRO among the series I stayed in for this story). But after spending time with Elliot and others in the Aranda, I realized his new habit might not be such a bad idea.

Drug dealers, prostitutes, and petty thieves frequent its halls. But the Aranda does have its advantages: the elderly and disabled are given rooms on the lower floors, making it easier for them to come and go as needed, while younger tenants are located upstairs. The top floor (the sixth) is the roughest – I was on the fifth floor, lucky me.

I first met Elliot – a dapper gent with blue-painted fingernails in Linda's room across the hall from mine. Elliot, Linda, and I spent hours discussing Voltaire; his screenplay company, Homeless Heroes; his current screenplay, "Sixth St. Woman"; prostitutes; and, of course, heroin and his own middle-class fear of the drug that used to keep him away from it.

"I've been reading the Harm Reduction Coalition's book," Elliot said rather academically. "When I'm shooting up, I follow their guidelines."

But Linda, a middle-aged woman from England, said she doesn't share Elliot's feelings about SROs. "I'm just waiting for a couple of things to come through, and I'm out of here," she told me before Elliot showed up. "I don't like it here; I've only been in America for three months, the whole time in this hotel, and it's just too sad." She wouldn't tell me what circumstances led her to the Tenderloin for her stay in the United States.

Things were slightly different at the Hillsdale Hotel on Sixth Street. The Hillsdale's owners keep the place on lockdown, and nobody gets past the front gate without proper ID. However, once you spend some time inside, things quickly resemble the notorious dirt and drugs of Sixth and Market.

My next-door neighbor at the Hillsdale was John, who said he's a former employee of Cisco Systems who survived three rounds of layoffs before finally losing his job. He's been a tenant at the Hillsdale for the past two years, while surviving on $400 a month in General Assistance. The rent for his room is $600 a month, and he now owes the hotel owners $3,700.

John's broke, and his room stinks because of it. "I haven't been able to do my laundry in a year," John told me while sitting on the small patch of bed not covered with the pile of hoarded objects that reaches the ceiling. That same night John and his girlfriend stay up until 7:30 a.m. doing speed while debating Christianity versus witchcraft.

Once somebody like John or Linda is stuck living in an SRO, it's not easy to get out and find a room in a neighborhood like Noe Valley or Bernal Heights. Even though the prices might be comparable and the conditions unbelievably better, landlord requirements like deposits, first and last months' rent, credit checks, and references make it nearly impossible for these people to get out of the Tenderloin.

The lack of options in places like the beer- and piss-drenched Aranda and Hillsdale Hotels makes Elliot's decision to self-medicate hardly shocking – or maybe only shocking that he didn't do it earlier.