Confessions of a Shopaholic

Rebecca Bloomwood is a shopping addict who lives with her best friend Suze. She works as a journalist for a gardening magazine but dreams of joining the fashion magazine Alette. On the way to an interview with Alette, she buys a green scarf. Her credit card is declined, so Rebecca goes to a hot dog stand and offers to buy all the hot dogs with a check, if the seller gives her back change in cash, saying the scarf is to be a gift for her sick aunt. The hot dog vendor refuses but a man offers her $20.
When Rebecca arrives at the interview, she's told that the position has been filled internally. However, the receptionist tells her there is an open position with the magazine Successful Savings, explaining that getting a job at Successful Savings could eventually lead to a position at Alette magazine. Rebecca interviews with Luke Brandon, the editor of Successful Savings and the man who just gave her the $20. She hides her scarf outside his office, but Luke's assistant comes into the office and gives it back to her. Rebecca knows the game is up and leaves.
That evening, drunk, she and Suze write letters to Alette and Successful Savings, but she mails each to the wrong magazine. Luke likes the letter she meant to send to Alette and hires her. Rather than completing a work assignment for a new column, Rebecca goes to a clothing sale. While inspecting a cashmere coat she has just purchased, she realizes it is not 100% cashmere and she has been duped. This gives her an idea for the column, which she writes and sent it to Luke. When asked if the article is to be published using her name, Rebecca refuses to use her real name and Luke creates the name "The Girl in the Green Scarf" and it as well as the article became an instant success.
Rebecca later returns home to renewed confrontations with her debt collector, so Suze makes her attend Shopaholics Anonymous. After one shopping spree she meets a friendly woman, Miss Korch, only to learn that she is the group leader and forces Rebecca to donate all the clothes she just bought, including a bridesmaid's dress for Suze's wedding and a dress for a TV interview. After the meeting Rebecca can't afford to buy back both and buys back the interview dress. During the interview, the debt collector is in the audience and confronts Rebecca. Successful Savings terminates Rebecca's column after the public confrontation for bringing discredit on the magazine and believing she is a risk for not paying debts. Suze is angry when she finds out that Rebecca lost the bridesmaid dress, and Rebecca feels like she let everyone down. Rebecca's father, Graham, is more sympathetic, making a remark that the United States has not fallen despite its gigantic national debt, and offers to sell his recreational vehicle to help her. Rebecca declines his offer, saying that he earned the camper through years of hard work and saving, and that she will need to tackle her debts on her own. Alette offers Rebecca a position at the magazine, but she declines. Meanwhile, Luke starts a new company, Brandon Communications.
The members of Shopaholic Anonymous promote Rebecca's clothes sale, which generates a lot of revenue, but not enough to retire her debts. She finally sells her green scarf when a woman bids on it, making it possible for her to give all the cash to the debt collector, which she pays in pennies - to give it to him in the "most inconvenient way possible".
Rebecca attends Suze's wedding after reclaiming her bridesmaid dress, and Suze forgives her. Luke returns the green scarf to Rebecca after revealing that the person who bought it at an auction was acting as his agent. Rebecca becomes romantically involved with Luke and starts working at his new company.

Question: Why is Rebecca disappointed with the clothing sale she went to?