It's like hunting morel mushrooms. At first you don't see any, because you don't know where and how to look. Then you figure it out, and suddenly they're all over the place. Sad to say, the wine world is chockablock with underachievers. Actually, it's pretty easy.
Most wines have direct competitors.
In a place like Burgundy, for example, nearly all the vineyards have multiple owners. You don't have to taste many bottles of, say, Meursault Charmes to know that one grower is delivering impressive goods while another is coming up empty. Broader-scale spots, such as whole districts, offer similar opportunities for comparison shopping. When it comes to famous districts, demand outstrips supply. There's always somebody who will buy a crummy wine as long as it's got a prestigious label.