ONE OF THE BIGGEST problems in education today is grade inflation and the devaluation of the B grade, according to education expert Wendy Mogel ("The Blessing of a B Minus"). "I travel around the country and hear high-school students say 'I feel like my future is doomed' if they get a B," she said.

Winemakers today might be excused for feeling the same way. The wine-rating equivalent of a B grade (85-89 points) can mean a wine might be hard to sell or might not show up on certain store shelves, especially when the competition scores 90 points or more. For example, when I asked Chad Watkins, assistant manager of Gary's Wines in Wayne, N.J., to recommend "a few good 88-point wines," he couldn't help me since "90 is the lowest number on our rating filter."

Wine scores have come a long way since critic Robert M. Parker Jr., their most famous proponent, first popularized them decades ago in his Wine Advocate newsletter. Mr. Parker, inspired by Ralph Nader, wanted to empower consumers against the insular, elitist world of wine. As he says on the front of his newsletters today, "Scoring wines is simply taking a professional's opinion and applying some sort of numerical system to it on a consistent basis. Scoring permits rapid communication to expert and novice alike." (The 100-point system is really a 50-point system, as all wines earn 50 points simply for showing up.)

Although the difference between an 88-point wine and a 90-point wine may seem like a fine distinction, "it's the job of a critic to make fine distinctions," said Thomas Matthews, executive editor of the Wine Advocate's chief competitor, the Wine Spectator. "A wine with some distinctiveness and concentration is very good, in the 85-89 range. And if it's a little better than that—if it has personality and some ageability—it's outstanding. That's a 90-94 point wine." And what earns 95 and above? "If tasting the wine gives you an emotion—surprises you and teaches you something—then it's an A-plus, over 95 points," Mr. Matthews said.

Distinctiveness and concentration are all well and good, but at K&L Wines in California, Burgundy buyer Keith Wollenberg says that if a wine received an 87, he isn't likely to publicize the score. If it got a good review as well, Mr. Wollenberg might post the review without revealing the score. "The wine will sell better without the number," Mr. Wollenberg said.