The WaPo writes of the apparently common phenomenon of mislabeling food. The anecdotes (and there are many) fall into two categories: fish, and premium foreign foods. Between 1988 and 1997 a study found that 34% of all seafood sold was "mislabeled and sold as a different species." As for the high-priced specialty items, it's things like caviar and honey (like heroin, it's cut with sugar). "Legitimate" manufacturers are, naturally, clamoring for government intervention. The customers and vendors don't seem to notice:
Still, of the hundreds of customers who bought 10 million pounds of mislabeled Vietnamese catfish -- including national chains and top rated restaurants -- only one or two caught the deception, said Assistant U.S. Attorney Joseph Johns, who prosecuted the Fairfax fish importer. "It was the rare exception, not the norm," he said.
Can you tell the difference between Vietnamese and domestic catfish? How about the difference between 100% honey and a 90% honey/10% sugar mixture?