Man, try returning a computer, especially a broken one. A true conversation:
"This system doesn't work."
"Right. That's why I'm returning it."
"We can't take it back if it's not working, it means we can't put it back on the shelf."
Facepalm. And reasoned argument, escalating into rather loud voices until they give me my money back just to get rid of me. Do not ever, ever buy a white box computer at Fry's.
I don't use that CC any more.
I've encountered the same receipt-checking at Guitar Center on the rare occasion when I've shopped there, and GC's employees also work on some sort of screwy commission system that at least superficially resembles a sweatshop. I suspect that there are some kinds of fiddles that involve ringing you up for one item and walking you out the door with another.
As a matter of principle, I always walk directly past receipt checkers at store exits. I've never been stopped, although I've gotten some nasty looks.
I believe that doesn't happen often, so I don't doubt that it hasn't been an issue for you so far, but it doesn't mean it will never be an issue.
Your choice of course.