For one of my winetasting groups, The Pompous Twits, I hosted the March event each year, and my theme one year was a blind tasting called "Classic Reds," featuring two examples of each of seven classic wine types: a couple of Cabs, a couple of Merlots, a French-style Pinot and a West-Coast-style Pinot, a big Zin, two Bordeaux, one in each style, an Australian Shiraz, and so on.
Your job was simple: Identify the grape. Is it a zin? a cab? a merlot? Or in the case of the French wines, is it a Bordeaux? a Burgundy?
Two years running, 15 wines, 15 participants -- a five-way tie for first place with -- five right. Yes, the top scorers--among people who are longtime wine buffs, visit the wineries and the Chateaux, know the winemakers, really know their stuff--got a third of them right. Correction: Guessed a third of them right.
This being The Pompous Twits, they weren't mad about it -- they were amused. "I was wrong about that one? No kidding? Oh well -- Pour me some more, it was good!"
I thought surely you should be able to tell a Rosenblum Zin from an Australian Shiraz! No, you can't. Maybe if I tell you that one of these two glasses is a zin and the other a shiraz, yes you could figure which is which. But you can't pick out the Zin from 15 wines! Astonishing. Which is why I repeated the experiment the following year, with the same results.
Mind you, these were each classics of their kind--I wasn't pouring weak-kneed Zins to confuse you into thinking they were Merlots--no, these were Rosenblum Rockpile Road Zins, as big as they come, and the others were the same: When you think of a wine, this is the one you're thinking of.
Supposedly highly trained professionals can tell wines apart, and even tell you details down to an improbable level. But short of them -- the other 99.9% of us can't.