Unfortunately, people treat the stores as gemach. My sister and her friends do it all the time. They “buy” a dress for a simcha and then return it. The Wal-Mart near Monticello was treated by bungalow families as a toy gemach. Taking advantage of Walmarts liberal return policies, toys were purchased at the beginning of the summer, returned at the end.
Giving only store credit deters this practice. The owner of the Boot Park dress shop where my wife bought a dress told her she offers store credit only because she was tired of being a gemach ( and the returnees didn’t even bother to have the dresses cleaned before returning them)