One of the quirks of the human condition is that we enjoy, even crave, flavors and textures which are polar opposites, often at the same time.
And that is due to our completely inadequate sense of taste.
Ah, sweet and sour mystery of life.
You probably think you do a pretty good job with your palate in seeking out subtle flavors and nuances in all kinds of foods and drinks. Well, quite literally, the job you do stinks. Hey, big fella, sit down and relax. Those are not fighting words. Not with me anyway.
More than 88% of all the tasting we experience actually comes through our nose. 88% is a big number. And, to add to the situation, our nasal abilities are not as keen as dogs or cats in the wild (no, not the kind that inhabits a certain karaoke bar on Bourbon Street), but we do a pretty good job of seeking out a wide range of flavors with our nose.
I know, there is a reason you did not take that second course in Biology and this is beginning to sound like the complicated mess you had hoped to avoid while looking for a crib grade. Press on. Pour yourself a glass of wine, or a solid cocktail, and let’s go over this whole affair.
Your mouth can discern only five things: sweet, sour, salty, bitter, and umami. The first four are self-explanatory. The last one, umami, is the sense of taste, maybe with texture, that one experiences from glutamic acid, like monosodium glutamate. It’s the way meats, cheeses and even potatoes taste after some process. Bite into a raw baked potato. Now bite down on one that has been baked. The product’s complete change is in the texture and the taste is due to the binding of certain agents during the preparation process, in this case the baking.
Anyway, that’s it for taste. You have five abilities. Taste buds are all over your mouth, particularly the tongue, but they are only finding those five tastes. Lazy little devils. Even insects have a better sense of taste than humans.
You experience sugar right on the tip of your tongue. Salt just a little further back, in the middle on the tongue’s surface. Sour is primarily discerned on either side of the tongue, with bitter towards the back. Umami, being more textural, is an overall sensation probably involving quite a few of your taste buds all over the place.
But, you, dear intelligent reader, will ask, “Where am I getting all those identifiable tastes from, like apples and cherries and beef and asparagus?” So smart to inquire.
Your nose, of course. Sort of a way to back into this proof is when you note that you have a bad cold and you can’t taste a thing. Taste does not vary all that much, unless your buds are stressed like from a hot beverage. What keeps you from tasting during a bad cold is that your nasal passage is all glopped up (technical term) and blocked. You cannot taste because you cannot smell.
Try this out: close your eyes and then tightly hold your nose closed. Ask a trusted friend, hopefully your wife or husband, to put into your mouth a pungent candy. Chew on it. What flavor was it?
If you kept your nose blocked, you won’t be able to discern with your mouth if it was sour cherry, bitter lemon, or apple. What you will get is sugar, no fruit.  
I know that many of you will be tempted to assign this shortcoming in the human condition to explain the Jagermeister® phenomenon. I will not be joining you in that discussion.  And it is not because I like that particular liqueur. Not by a mile.
Now, back to our original thought. Many of us take our iced tea and add both lemon and sugar. Some people, and you know who you are, like sweetened tea, which contains a superabundance of sugar. Those are opposite flavors, but we add them in order to achieve a balance that is pleasing to us when enjoying an acidic beverage like tea or coffee.
Our particular array of taste buds craves the ying and the yang of both sweet and sour. Our tongue can do the work here, with some assistance from our nose.
What is the first thing people with little or no wine knowledge ask for in a new wine? Yep, they want something “dry.” They don’t think they like sweet wines. These are the same folks who like sweet tea and Coca-Cola®. At this point, science and logic part ways.
Even in spirits, we seek balances between sweet, sour, salty and bitter. You would never build a cocktail around Bitters. They become an important, but minor, ingredient in the overall cocktail building process, with spirits taking center stage, along with an array of supporting characters like sweet mixers, fruit, vegetables and whatever else. But just about everything you add to a cocktail for taste has to be balanced with an ingredient of opposing flavor. Balance is the key to great cocktails.  
Wine is also an interesting challenge since it is a stand-alone beverage and lacks salt. You would have to drink more than 100 bottles of wine to reach your recommended daily intake of salt.  But there are enough other naturally-occurring tasting and odor elements to keep it interesting.
Every day is a Big Surprise and so we seek comfort and routine. Sugar and lemon in a bitter acidic drink makes us happy. Finding sour cherries or apples in the bouquet of wine is a fun quest.
And now you know why it is proper for you to stick your nose into a glass of wine before you drink it, or why bringing a well-made cocktail slowly to your lips, allowing your nose to get involved with the aroma, is important.
You’re human. It’s how we do things.