And to put in terms of real-life - in Shenzhen, China I've seen people selling whole spools of "QC PASS" stickers, as well as any logo or guarantee label you want.
To be fair, QC pass stickers are going to be sold like that just because you'll need a lot of them if your only way of identifying pass/fail is via a sticker. I don't see why you wouldn't buy those en masse, and use them on a real assembly line -- especially in a country where most plastic goods are produced.