> This seems impossible. Returns require a receipt. I don't know what you're talking about.

1. Buy item #1, obtain receipt, take it home

2. Go back into store, find identical item #2, take it past checkout counter and up to return counter

3. "Return" item #2 using receipt for item #1

4. Profit

For big ticket items there's usually a unique serial the store will scan to prevent this sort of thing, but not always. Pretty deplorable.