THE MACY'S SALESCLERK gaped in amazement. A young black-haired woman was staggering toward her counter, loaded with shopping bags. The customer began pulling robes from the bags, piling them on the counter.

"I just got out of the hospital," the customer whispered. "I'm very sick. It's bad for me to get upset. These robes were presents, but I can't stand to look at them. They remind me . . . they remind me . . . "

The salesclerk refunded the money. At the Saks Fifth Avenue children's department, the black-haired woman began pulling baby clothes from the bags. Sweaters. Little pants. The salesclerk looked suspicious.

"My father is an alcoholic," the woman said earnestly. "He goes on buying binges. He bought all this stuff with my mother's money, and I have to bring it back."

Finally, at the B. Altman's tie counter, a salesclerk guessed the truth.

"What production company do you work for?" she demanded.

WHEN the Bring-'Em-Back Girl goes on acting auditions this is what her r,esum,e says: Carrie Kronish, 25, 5 foot five, 135 pounds. She has appeared in "Maid of Honor" at the New York University Playwrights Group and in "Middle of the Night" in the Open Scene Workshop. She was once an extra in the soap opera "One Life to Live." In the movie, "Six Weeks," she says she "stood in the lobby of the Waldorf-Astoria."

These days the Bring-'Em-Back Girl performs for audiences of one: clerks in New York department stores.

Bring-'em-back girls work for production companies. They're a key reason commercials look slick and glamorous. "The companies need clothing for commercials," says the Bring-'Em-Back Girl. "You need one tie, you buy 40 to see which is best. A robe? You buy 12. Afterward the used clothing is smeared with makeup, so the company keeps it." Everything else is given to the Bring- 'Em-Back Girl.

Today, the Bring-'Em-Back Girl is returning clothes left over from an Aqua Velva commercial. She has brought back as much as $5,000 in clothing in two days. She has returned jackets nobody wore in McDonald's commercials and shirts nobody wore in Harrah's commercials. She earns $100 a day plus meals. It beats waitressing. She gets to meet directors who someday may hire her to wear the clothes instead of bringing them back. She is an apprentice, on the low rung, in the world of illusion.

In the commercial-making business bring-'em-back girls are also called "return girls" or "professional bag ladies." "Success is all in the personality," Kronish says, although pure acting talent doesn't hurt. "Store policy says salespeople have to accept merchandise anyway if you have a receipt, but we're encouraged to make up stories. There's less hassle that way. And it keeps the stores from changing policy."

The stories are often clever -- "Oh, you like Michael Jackson? That's amazing because we just shot a commercial and you see this video I want to return? He touched it!" Or the stories can be brutal -- "My sister's leg was severed. She can't wear pants anymore."

The Bring-'Em-Back Girl is not married. Her father lives in Westchester where he neither goes on alcoholic binges nor steals her mother's money. Her sister has two legs, although the Bring-'Em-Back Girl gets superstitious sometimes that maybe her sister could lose a leg as punishment.

"She's a well-rounded person, a talented girl who will do well in the business," says Ed Libonati, head of Libonati Productions and a recent employer. A novelist who knows her says "she's sensitive." A glance back at her r,esum,e reveals a humorist: Last on her list of hobbies is "dieting." She does not like to lie.

As she lugs bundles of shopping bags past little boy mannequins, by displays of smart women's clothing, past department store salespeople spraying perfume samples on customers, the Bring-'Em- Back Girl philosophizes: "Everyone is acting, not just me. The salespeople, too. It's their job. I would never take advantage of people."

She is rationalizing, trying to fit her ethics into the job. Sometimes it doesn't work. While getting ready to return baby clothes, the Bring-'Em-Back Girl pulls a pink pajama suit from a bag and holds it up. "How old does a kid have to be," she asks me, "to die of crib death? Is this too big? It is?"

The Bring-'Em-Back Girl approaches a formidable-looking salesclerk in the children's department. Mostly she just says merchandise "wasn't right." She has antennae for doubters. Sure enough, here comes the suspicious question. "Why are you returning these?"

Her big brown eyes droop: "The child died."

The salesclerk's mistrust turns to horror. She disappears into a curtained alcove to process the return. The Bring- 'Em-Back Girl suppresses a smile, then lets down. The setting has begun to work on her. She is surrounded by baby clothes -- cute little nightgowns, tiny pants.

The Bring-'Em-Back Girl slumps on a rack, chin against wrist. Her eyes water. She cries: "I feel horrible. This is what always happens."

THE Bring-'Em-Back Girl staggers from Libonati Productions with load number two of the day. The set is dark now; the beautiful actors have gone home to their cramped Manhattan apartments. The Bring-'Em-Back Girl is on her way back to the stores. Says Libonati: "Macy's is the biggest prop shop in town."

Carrie Kronish gets into a cab and gives the driver the address of Bloomingdale's. She feels sick. "I'm thinking I don't want to do this. I hate the hassle. I've been debating with myself. Which is worse: Waiting on people while I try to get parts, or lying and cheating?"

The Bring-'Em-Back Girl can no longer base her happiness on illusion. "I've decided to quit," she says.