Suppose you had reason to believe that a yarn from a reputable manufacturer was mis-labelled as to fiber content. Suppose the inaccuracy was in a direction that would likely diminish the perceived value of the yarn. Suppose it was, no matter what the fiber content, a good-quality yarn: soft, easy-care, good stitch definition, good pattern support. A yarn that sold fairly well--not your best-selling yarn, but not your worst. (Oh, by the way--in this dream, you own a yarn shop.)
Now imagine that someone brings it to your attention that it's illegal to sell inaccurately-labelled yarn. Not just illegal like someone could sue you because they felt they'd overpaid since the yarn isn't "really" cashmere, but illegal like the government could fine you $5,000 for each skein sold.
What would you do? Sell it without labels, as "mystery yarn"? (Not strictly legal: yarn must be labelled for fiber content, weight, etc.)
Throw it in the dumpster out back? (Seems an awful waste: it's still good yarn.)
Donate it to the next worthy charity that comes knocking? (It's not suitable for all purposes.)
Take it home and add it to your private stash? (There's a space issue. We're talking about a significant amount of inventory. And do you want to knit at the same gauge for five years after you retire?)
Leave it on the shelves, on the grounds that experts are still debating whose fiber-content tests are more accurate? (Strictly speaking, it seems that you're liable even if nothing's been "proven" in court, as long as you had reasonable cause to suspect.)
Require each customer who purchases the yarn to sign a waiver of their right to sue, should the yarn prove not to be the stuff they thought it was? (Again, we're not just talking about civil suits; the long arm of the law could still come after you.)
In case you're wondering: yes, there are two ways in which the supplier could have assumed the responsibility for the situation: by providing a very specific legal warranty that the yarn is in fact accurately labelled, or by acknowledging that the yarn is not accurately labelled and providing replacement labels indicating the true fiber content. Let's assume for the moment that neither of these bail-outs from the supplier is forthcoming.
The really unfortunate thing* about this is that it's still good yarn no matter what its contents. But there doesn't seem any way to continue to make it available to customers without exposing the seller to potentially disastrous consequences.
So what would you do?
[*Note: I'd almost written "The tragedy about this is . . . " But then I thought better of it: this isn't a tragedy in any way, this is just some combination of greed, dishonesty, and pettiness. And one reason it's all going to go so badly--and stay tuned; believe me, it's going to go badly--is because so many people are going to behave as if 3% or 5% or 7% cashmere in a yarn, or not, is the equivalent of the Watergate coverup.]