It shouldn't be that hard to differentiate between worn returns and unworn returns. Her policy should be all unworn clothing can be returned with original tags.
This is not a frum problem IMO. All department stores have this issue with non Jews as well wearing dresses once and returning them knowing they will never wear it again. So now instead of discriminating, Bloomingdales and lord and Taylor put tags on the outside of a dress so you cannot wear the dress without removing it and once it is removed you cannot return the dress.
I don't see them getting any heat since they did it the right way.