Everone of a certain age enjoys a few foods, drinks, and other orally-injested substances that, when first tried, were simply unpalatable. Coffee is a good example of this, though maybe not the best example. More on that later. In any case, this class of substances is known as "acquired tastes."
Most acquired tastes are bitter substances. We don't like bitter things because poisons are traditionally bitter. Poisons such as caffeine. After all, a tiny but of caffeine will easily kill a person. It's also one of the most addictive substances we know of. And yet, we love the stuff. What's wrong with us?
The thing we know best about caffeine is that it provides us with some handy if imperfect benefits, like giving us something of a wakefulness boost. Conditioning being what it is, if we taste something that disagrees with us, followed by a pleasant sensation, then eventually we'll come to like what we tasted.
I mentioned that coffee was not a perfect example of this, because coffee only tastes bad when it's prepared improperly. There us so much great flavor in coffee that the bitter should just be an underlying note.
Which is, incidentally, another way that tastes are acquired. You taste something terrible, but sense another taste underneath that is really good. Conditioning happens again, until you not only look forward to the underlying taste, but the bitter taste as well.
The photo accompanying this article is of a beer float, which combines a bitter stout beer from the Highland Brewing Company in Asheville, NC with a stout beer ice cream from the Ultimate Ice Cream Company. Depending on how you combine the ingredients, you'll often start with a bitter hit, then have that mellowed out by the ice cream. As you go on, you appreciate the dish more and more. It's a very quick way to acquire a taste.