A little over three years ago, desperate for extra cash to supplement my live-in job as personal assistant to a well-known Berkeley academic, I answered a San Francisco Chronicle ad calling for "mystery shoppers." Unlike similar ads in the back sections of free papers -- one of which suckered me into calling a Dominican Republic phone number and shelling out an extra $25 to Pacific Bell -- this one had been placed by a reputable Bay Area private investigation firm. I went in for an interview the next day and was hired on the spot. If I remember correctly, they drooled at the sight of an actual, not to mention recent, college graduate.

I'm still working for them. Although the job has rarely, if ever, kept me in pocket money, it has forever changed my perspective on jobs. As a mystery shopper, I get paid to down free food and drink -- while keeping a very careful eye on the scenery. Once assigned to an "establishment" (our term for dives and ritzy places alike), I function as an "Operative", watching employees to make sure they're neither giving out nor taking in any unauthorized money, alcohol, or food. Basically, I'm a very minor narc, and as such, receive hardly more money -- but considerably more freedom -- than the employees on whom I'm asked to rat.

While on duty, I tend to frequent the same areas of town that tourists do, and for what it's worth, I probably understand a San Francisco tourist's perspective better than most residents do. I get sent to Fisherman's Wharf on a regular basis, sometimes in disguise as a European tourist complete with accent. Since my physical type is somewhat out of the ordinary -- I'm a tall, pale redhead -- I've even been asked to wear strange wigs and glasses to avoid being recognized and treated as a "regular."

At first, all this rigmarole had me continually worried that I would somehow get caught in my act, that I seemed too out of place or lonely or just plain weird to be real. Wouldn't some merchant or other eventually identify me as the beanpole redhead who always buys two drinks but sits alone? Then one evening when I was off duty and grabbing a bite to eat at Mel's on Geary, I saw a thirtyish woman in an obvious wig sitting for over forty minutes in a battered green Cadillac with the motor running. Family after family of freckled kids and gaggle after gaggle of Asian American teenagers parked their cars in the lot or their butts in the outdoor seats on the concrete patio. Everyone's attention was focused on their burgers or the '50s chrome fixtures, but no one even looked at the woman, except me. I realized two things then. The first was that waiters and bartenders in a major city have seen absolutely everything. It doesn't take much to pose as a customer -- anyone who buys something is a customer -- and so by that definition, I wasn't any more of a poser than some businessman who charges meals to his company.

The second realization was that the mystery shopper position suited me pretty well. A writer's eye is an observant eye, and whether or not I'm being paid to take down details, my knee-jerk reaction is to do so.

Still, I wondered about some of the employees I'd helped put under with my evidence. Like an unpunished criminal who seeks out his former victims with the aim of atonement, I wanted to know what they thought of me. My reluctance to breach my employers' confidence, not to mention my desire to retain my teeth, kept me from going back to a former client and asking the bartenders just how obvious my narc-ness had been. But I did speak to two employees at bars I've never shopped (and now, never will shop), and asked them about their recent brushes with secret shoppers.

At the preppy, posh Harry's on Fillmore I talked to Jim, a thirtyish boy-next-door type who has been tending bar "off and on for four years." He immediately set me straight on my terminology: apparently what I've been doing in bars is called "spotting" and not "mystery shopping" -- the latter is a term reserved for undercover activities in retail stores. He said that twice he has been hired to replace employees who were thrown out due to incriminating spotters' reports, but he was a bit indignant when I asked him if he'd ever been able to spot a spotter: "Not necessarily, no -- I don't worry about that," he answered.

"Of course you don't worry about that!" He seemed quick to anger, so I immediately alleviated any implication that he might be involved in illegal activity. In fact, I left feeling significantly less honest than him. He spends his time serving people. I spend mine watching bartenders like insects and hoping that, if only for variety's sake, they'd break a few glasses or pocket a chunk of cash.

Maybe bartenders are, as a breed, less paranoid and neurotic than mystery shoppers tend to be. At the candlelit Hush-Hush in the Inner Mission, Cynthia, a long-haired, petite twentysomething who wasn't sure how long she'd been tending bar, was equally clueless about the terms "mystery shopper" and "spotter." I defined them for her somewhat reluctantly, knowing that I might alter her perceptions of bar patrons from that day forward. She laughed. "Ohmigod I had no clue," she said.