[What you need to know to start the day: Get New York Today in your inbox.]

Chérie Celeste Malone was a struggling actor who had been piecing random jobs together — waitress, barista, rental property manager. Then she saw a casting call on Backstage, a jobs website for actors. She went to the audition, but to her confusion, didn’t have to read any scenes. She was hired immediately.

But she had misunderstood the ad: It wasn’t for an acting role, exactly. The job was to be a “brand ambassador” at marketing events. And it paid, in her words, “extremely, extremely decently.”

Ms. Malone, 27, had stumbled into a thriving industry that seemed ideal for people like her: the world of experiential marketing, which aims to create emotional connections between people and brands through real-life interactions. These happenings rely on temporary workers who function as something between event staff and human billboard.

Called brand ambassadors, or B.A.s, they’re the smiling (and suspiciously attractive) people greeting visitors at product launches, handing out free samples at music festivals, signing in guests to fashion shows, or appearing out of nowhere to chat whenever a long line forms, making sure people don’t get bored.