It's wrong to do things that will cheat a business.
Karen has spent many years shopping at a store that offers a very generous return policy.
Karen wants to return a TV.
Karen returns the TV she bought a week ago in exchange for one that better suits her living room.
Karen returns all of the TV's in her home after years of use, in exchange for new ones at no cost to her.
The store's return policy is able to remain as it is for years to come.
The store realizes what Karen is up to and cracks down on their return policy which changes things for everyone else who shops there.