Employees from Costco, Walmart, and Target share their worst horror stories — and they'll make you rethink how you act when you shop

• Walmart, Target, and Costco employees— as well as workers at all retail stores — sometimes come up against pretty difficult customers.
• Business Insider spoke with a number of retail workers about some memorable and negative experiences they've had on the job.
• Their stories just go to show that it's always a good idea to be courteous while shopping.

Walmart, Target, and Costco employees have seen some pretty gnarly things on the job. Many retail workers, in fact, can probably think up at least one or two less-than-positive incidents they've experienced while working a shift.

Oftentimes, customers are at the center of these troubling situations. A study from the University of British Columbia found that we tend to treat retail workers worse when we're hunting for bargains.

Business Insider has heard from a number of current and former retail employees who had stories to share about particularly gross, bewildering, or nightmarish scenarios that unfolded during their shifts.

The employees we corresponded with have experience working at Walmart, Target, Costco, McDonald's, Macy's, Home Depot, and other retailers. Their stories just go to show that it's always a good idea to be nice, even if you're not having the greatest shopping experience.

Here's what retail employees had to say about the horror stories they've experienced on the job:

SEE ALSO: Costco employees share 21 things they'd love to tell shoppers but can't

DON'T MISS: Costco employees share the 20 things they wish shoppers would stop doing

SEE ALSO: Target employees share the most ridiculous returns they've seen customers make

A luggage store employee was cursed at over a suspicious return

"It never ceases to amaze me that the stupidest people I've encountered are the ones with university educations," a former retail employee from Ontario told Business Insider. "And the smartest ones have at least five years of retail under their belts."

One day, while working at a small luggage store, a customer came in to return a bag.

"Like any place nowadays, there is a form to fill out, and the purchase must be returned to the credit card used," the former employee said. "Store policy."

The shopper, however, gave the employee a phone number instead of a credit card number. She said the card was at home with her husband.

"I informed the woman that we cannot do a return onto a credit card over the phone, we need the card there to swipe through the machine," the former employee said. " She proceeded to call me a stupid b****."

An A&P employee witnessed a woman getting thrown out of the grocery store

A former employee of A&P, a now-defunct chain of grocery stores, described watching a parent leaving her two children in line at the register for an extended period of time. The cashier ultimately had to skip over her purchases and ring up the people in line behind her.

"She returned and not only demanded to be served immediately — despite the fact that this would mean voiding a large transaction — but also began loudly chastising her kids for not keeping their place in line."

The situation escalated to the point where the store manager intervened and told the woman to leave and not come back, according to the former employee.

A former Victoria's Secret manager had to reject a shopper's ancient return

A former Victoria's Secret manager told Business Insider about a time when a shopper came in to return a bra.

At the time, the former manager said that any Victoria's Secret bra could be returned, as long as the item wasn't excessively worn or defective.

"This customer comes in with a bra in a grocery bag and turns it out on the counter, saying that she wanted to return it," the former manager told Business Insider. "The bra was totally worn. It used to be red and now looked gray. Plus, it had deodorant stains all over it."

The customer explained that the bra was her mother's. The former manager asked the shopper to provide a receipt.

"She looked at me like I was crazy and said she didn’t have her receipt because it had been years since she bought the bra," the former manager said. "I explained to her that we did not even carry that style any more and that I could not take it back."

The customer proceeded to snatch back the bra and storm out of the store.

"I had to run to the bathroom and scrub my hands with hot, soapy water after touching that nasty bra," the ex-manager said.