As Maya put it in Sideways, wine is a living thing. And she’s right: as it arcs through a youth, a middle age, and its golden years, every wine changes. And then, like all living things, it dies. So in the case of a good wine, or more specifically a fine wine that’s meant to last, the surprising answer to my titular question is never.

Even if it’s an ancient wine, robbed by the years of all its fruit flavors, and reduced by oxygenation to vinegar and alcohol, it’s not bad, just expired. I mean, you would never say of Diane Keaton for example that because she’s lost her figure she’s gone bad. She just plays a different role in your entertainment. Similarly, you would not say of ex-President Reagan that because he passed away he’s become pernicious; on the contrary, he’s now a legend. It’s the same with wine.

Now if any wine (fine or otherwise) is corked, cooked, or otherwise damaged, that wine would be bad, and you’d be correct to send it back in a restaurant. Or, if a wine is intact but not your style, then from your perspective you’re right to call it bad, but I wouldn’t recommend that you try to return it to the store you bought it from.

But a good wine is never bad. This was proved on me a few weekends ago by a very special old cabernet from the Napa winery Charles Krug.

It was a 1974 “Reserve Selection, Lot F1” that my neighbors purchased from the winery right after it was released. Krug bought the fruit for this wine from the Fay vineyard in Stag’s Leap, a magical plot that made history two years later when Stag’s Leap Wine Cellars’ version came in first at the famous Paris blind tasting, California cabs versus French Bordeaux.

The bottle itself was in perfect condition – no leakage, cork deterioration, or ullage – and it bore the signature of Robert Mondavi’s father, Cesare, once-patriarch at Krug, on the pristine label. Although this brick-red beverage had held up admirably through 35 years of Time swinging its scythe around its foil cap, I thought it had lost most of its fruit and was starting to taste a little alcoholic and acidic. Everyone else loved it, though, and I noticed that they drank it down to the pile of sediment at the bottom of the bottle, ’til they could drink no more. In any case, the wine had definitely not gone bad. To my companions it was toothsome, to me, a little long in the tooth.

Krug, by the way, is not to be confused with the French Champagne maker Krug — even if it was by my sister in law one morning, when she uncorked a bottle of Krug Grand Cuvée I’d got as a gift, thinking, she said, it was “only a [Charles] Krug.” The $200 replacement-fee lesson? Well, none really, since she and my wife’s parents couldn’t stop talking about how much they enjoyed that bubbly (my mother in law had two glasses, a rare event). Plus, when it comes to Charles Krug, there’s rarely an “only” to be said in connection with their wines. For years we were positively addicted to their “Generations,” a cabernet blend that was as delicious as it was affordable. We even liked their sangiovese, a difficult variety to make good wine from in California. And in the middle decades of the twentieth century Krug was considered, along with legendary wineries like Ingelnook and Beaulieu, to be one of Napa’s “Big Five.”