A middle-aged woman was showing a photograph around on the avenue where I was working. She was flagging down passersby, trying to find someone who’d seen a runaway teenager.

Out of professional interest, I moved to intercept the woman. She registered me coming and turned to make eye contact. Then her face quickly shut down and she turned away. She didn’t see a kind, interested stranger, much less a cop. She saw a hooker.

I couldn’t blame her. It’s what I’d intended.

Prostitution-decoy work was more commonly done by metro police departments, but there’s often a need for fresh faces, so I was on loan. Tonight I was posted on a heavily trafficked avenue south of downtown Minneapolis, not far from the business district, where undercover officers like me vacuumed up out-of-towners looking for a good time, as well as local salarymen leaving the bars after their end-of-day cocktails.

A civilian might have been surprised at how simply I was dressed. That’s one of the first things you learn: no miniskirt, no high heels, no seamed stockings. Genevieve had explained it to me, years ago.

“Street workers can’t afford to advertise themselves to cops,” she’d said. “Besides, I think a lot of them are just too tired. Psychologically, they can’t bring themselves to treat this like a job.”

So, early this evening, I’d pulled on a pair of jeans and boots, a white V-necked T-shirt, and a cheap reddish imitation-leather coat. The makeup, more than wardrobe, was important. I used a thick, pale concealer stick, not in trouble spots, as prescribed, but all over my face, creating an unhealthy pallor. After that came mascara and eyeliner pencil. “Eyeliner’s the best,” Genevieve had said. “Nothing ejects you from the ranks of the Camry-driving middle classes like eye pencil.”

The number one tip-off out on the street, though, isn’t your clothes or makeup but demeanor. It’s that guarded little bend from the waist that street workers do, looking through car windows. That’s what tells the men who you are.