Last week at a small private dinner, the host, a wine importer, brought forth a bottle of 1928 Château Desmirail, a third-growth red Bordeaux from the Margaux district. Normally, at such a “tah-dah” moment, the wine is presented with academic reverence about its historicity or fetishistic fussing about the condition of its cork.

But the first thing the host said upon presenting the wine was, “I bought this years ago, before there was any likelihood that anyone would fake a wine like this.”

Until very recently, anyone who bought an old wine, typically at auction, took it at its label’s word, as it were. If it said Château Lafite-Rothschild 1961, then it was so. If the wine proved disappointing, you assumed that it was either your inexperience as a taster or it was a bad bottle. After all, that can happen, especially with decades-old wines potentially subject to overly warm cellaring or an imperfect cork.

Today, however, more than a mere worm of doubt has insinuated itself. Instead, it’s a serpent in an Eden of wine innocence. The root of the problem is what the proverb has always told us: It’s money. Old wines from famous estates (nearly all European) now sell for extraordinary sums. For example, at a Zachys wine auction earlier this month, six bottles of 1945 Château Latour — a great vintage — sold for $78,210, or $13,035 a bottle.

That is a relatively paltry sum these days. Last month Sotheby’s sold a jeroboam — six bottles in one — of 1945 Château Mouton-Rothschild that came directly from Baroness Philippine de Rothschild’s personal cellar for $310,700, or the equivalent of $51,783 a bottle. I could fill the page with lists of wines that effortlessly fetch thousands of dollars a bottle, including some from California, Italy, and the Rhône, that originally sold for mere hundreds of dollars just a few years ago. The key point is clear: The incentive to counterfeit wines has exploded along with the prices.

It’s pretty easy to convincingly counterfeit an old wine bottle. Also, until recently, nobody was scrutinizing those bottles very closely, auction house protestations notwithstanding about their wine experts’ careful scrutiny of labels and concerns about provenance. The auction house wine buyers, many of who are knowledgeable, do catch the obvious ones, to be sure, but as in the art world, the really good forgeries slip through unnoticed — especially if buyers aren’t complaining.

What about the wine in the bottle, you ask? Who among us knows so much about old wines — or young ones either, for that matter — that we can declare with absolute certainty that the purported 1961 Château Pétrus is definitively as declared? A savvy counterfeiter can concoct a Pétrus-like red wine convincing enough to allow even a so-called expert to concede that it might possibly be the real thing, never mind a 20-something Wall Street whiz.

Wine has always been subject to counterfeiting. This is why we’re presented the cork when served a wine in a restaurant and why that bottle is opened in front of us. Until the late 1800s, it was commonplace for wine in restaurants to be opened away from the guests and served in a decanter. It’s easy enough to see how an empty bottle of Château Lafite-Rothschild could be filled with something much cheaper and passed off as the real thing.

It’s also why some wineries would wrap each bottle in a wire mesh, a practice you still see today with some traditional Spanish wines. This made it that much more difficult for a restaurateur to switch labels.

How was that 1928 Château Desmirail, you ask? It was amazingly fresh in color, more resembling a 20-year old red wine rather than something closer to an octogenarian. The 1928s were famously long-lived, and the Desmirail was consistent with the reputation of the vintage. The greatest assurance of its authenticity, however, was less a matter of connoisseurship and more a matter of the improbability of con. As the host said, he bought it long enough ago that it was unlikely that anyone would have bothered to fake it. So we took it for the real thing.