This is a fascinating discussion topic, and I'll throw in my two cents for the moment. I think they can be "trained" for instance if you take one chocolate a day, and take some time in each day to have a quiet place where you can concentrate, away from all kinds of odors and distractions. This can be at one of the palate peaks of the day, like 10-11 am or 5-6 pm or maybe even very early in the morning. Make sure your palate is clean with green apple, bread, and /or water, and that you haven't just had a big spicy or strong tasting meal. If you examine a different chocolate every day, carefully tasting and writing down some notes -- maybe even trying a small amount of this same chocolate several times during that day-- soon you will begin to really sense more and more flavors.There are many tasting games and exercises in Clay's book and Chloe's book and also online, which aim to help you develop and discern different flavors, like comparing side by side and so on. And perhaps others will offer suggestions here also. And important to realize that you will not taste all of the things the "experts" and critics do, and probably not as many notes either, at least not at first. After awhile you will begin to taste more notes, and this heightens your sense of taste gradually with other foods as well. When you really focus on something, you really tune in and appreciate the world of taste.One other thing is the whole supertaster issue. At this point there are considered to be three kinds of tasters in the world, the normal taster, the non-taster, and the supertaster. Non-taster, pretty bad designation, huh?But this is all about how many fungiform papillae, which have the taste buds, are on the tongue. If you have fewer than 15 in a 1/4" diameter space on the tongue then you are a non or under taster, 15-30 is normal, and then 30+ is super. But it doesn't mean that if you are a normal or under taster that you cannot develop and learn to taste the nuances of flavor, but you might need to be a bit more persistent and patient. And there is a little test to determine roughly where your tongue falls in this. Read about how to do this
here . I have done this cute little test and it seems I'm a supertaster, with over 50. About 25%, and more women than men, are supertasters. 50% normal, and 25% under.And also there are many not too complex chocolates in the world, so if one eats mainly those then they may not find many flavors there no matter their number of taste buds!