You are partially correct, partially not.
People can and often do return items to stores such as best buy, with limited or no play time. Often times the people who return them with "limited" play time say they have not been used, and often, the idiotic return person will agree and give them a full refund.
These products are packed back up, and resold.
However, they can't lie to you and tell you that the item you are buying is new when it was used for countless hours over a period of x years or x months. That would get them sued. However, that doesn't mean some stores don't do it.
If you have an inside source, I would believe you more. But if you're just going off your experiences or someone else's (even less reliable) then i am guessing that the situation i explained happened to you.
I used to work retail, and as long as it all looked nice and was still in "new/sorta-new" condition, it was resold.