Costco has a particularly generous return policy.

And there's a reason for that. One former Costco manager explained the reasoning behind the policy, telling Business Insider the "liberal return policy" created a sense of confidence in members.

"They know that if it does not meet expectations, they can return it," the person said. The chain hopes that confidence will prompt customers to shop and spend more.

What's more, the former manager said that despite the horror stores, the policy "is not taken advantage of as much as you might think."

"Being a membership club, the members have a vested interest through their membership fees to follow the rules," the person said. "Sales and returns are tracked and fraud is easy to spot. In these cases, memberships are canceled. Many times members would have rather me call the police than cancel their membership when caught shoplifting or committing return fraud."