OK. I interpreted this as a question about getting buzzed after so much wine that they start to blur together:
All I can say is, thirty years of experience has inevitably produced knowledge and skill, simply through practice and repetition. At this point I already know what I’m likely to buy, because I’m pre-selecting wine regions and specific wineries based on what I know about them, and I have a rough shopping list in my head before I even show up. I’m tasting because I’m still trying to learn the fine details — doing single-vineyard verticals, comparing year to year, that kind of thing.
Also, at this point, the challenge is pretty fun. When we were in Bordeaux, we went to one of the restaurants that does a blind wine course. With each successive plate, they give you a glass, and don’t tell you what it is; then they come back later and ask you about it. The first glass they gave us was a white, conventionally dry, but with an oddly pronounced flintiness. I told the server I was pretty sure it was a Pinot gris from Alsace, but there was something about it I couldn’t place. He said I was right, and the unusual character was because it was from the German side instead of the French side. Then, with the second course, the glasses he brought me diverged from what he was giving the rest of the table, uncommon choices intended to throw me off. It worked, too. The final glass with dessert was particularly baffling; it turned out to be an apple wine from Poland.
When you’re a wine nerd, this kind of game is wildly entertaining. Just trust me. 
You might be skeptical that these slight distinctions can be discerned, glass to glass, especially after a long day when your palate gets tired, but like I said, time and experience develops the necessary skills. I would compare it to any other similar discipline. Like, I don’t know the first thing about bird-watching. I can identify the boldly distinctive birds like blue jays and magpies, but beyond that, one little brown bird is just like any other little brown bird. An expert, though, can spend all day peering through his or her binoculars, rattling off identifications at a glance. I might raise an eyebrow at their confidence in instantly distinguishing a male gray-throated house sparrow from a female brown-tailed song sparrow* but the expert really does know.
*I made these up. Like I said, I don’t know anything about birds. But if you put a glass of Amarone and a glass of Margaux in front of me without telling me which is which, the difference will be night and day.