It tastes nasty to you, because your palette requires a high level of sweetness to go with the chocolate flavor.
It's common for people who eat a lot of sugar, junk food, or processed food to need a lot of sugar or salt to enjoy food. In other words, it's the norm for most Americans, and it's the reason people from other countries often find our food too sweet. The good news is that by eating natural foods, the tastebuds can slowly be awakened to a whole array of real flavors, and everything begins to taste much sweeter naturally without all the added sugar.
Dark chocolate is available in a huge range of sweetness levels, which can be defined inversely by its cacao content. I've seen chocolate with as little as 50% cacao called "dark chocolate," but it ranges from 50% to 100% cacao. (By comparison, milk chocolate typically contains about 30% cacao, in addition to its characteristic milk, of course.)
When I was a kid, I liked milk chocolate, but started to develop a preference for the delicious rich chocolateyness of dark chocolate. As dark chocolate became more popular in recent years, it also became available in a wider range of strengths. I soon went from preferring 65% cacao to 72% cacao.
My preference remained at 72% cacao until I tried eating all natural food, as part of our Crossfit gym's paleo challenge. When I switched to all natural foods, my preference for cacao content went up and up, as foods started tasting naturally sweeter and sweeter. I started preferring 78% cacao, then 85% cacao.
I now like 90% cacao the best, and sometimes I even enjoy 100% cacao chocolate. 100% cacao chocolate, when paired with fresh macadamia nuts, tastes to me like extra-chocolatey chocolate chip cookies. Milk chocolate tastes almost like cotton candy to me now, it's so cloyingly sweet.
So, what tastes "nasty" to you, is truly the most delicious dessert in the world to me.
If you ever decide to give dark chocolate another try, I'd recommend starting with a fresh, good quality dark chocolate from Madagascar, something in the lower ranges of cacao content. The beans from Madagascar are rich in flavor due to the volcanic soils. It gives the chocolate a very subtle berry flavor.
Fresh dark chocolate has a slight sheen to it, a velvety texture, and melts slowly in your mouth when it's at room temperature. If it doesn't have a slight sheen, if it has a slight white coating, and/or it doesn't melt in your mouth with a velvety smooth texture, it's probably stale. Stores that don't sell much dark chocolate often have stale chocolate, so don't buy it there.
High end chocolate specialty stores will awaken you to a whole new world of chocolate that you never knew existed.
I discovered this magical world when I lived and worked in downtown San Francisco for a summer (for those of you in SF: Fog City News, 455 Market St). They had free taste tests every Tuesday. <blink>
That was when I discovered the complex and delicious flavor profiles that chocolate from various processes and cacao beans from around the world can have, created by an endless variety of independent chocolatiers from around the country and even around the world.
When we went in for our free taste tests, we'd list all the flavor notes we could taste in each blind chocolate sample. The store manager who administered the blind chocolate taste tests also noticed that most people need a couple of "warm-up" bites of chocolate before they can detect the subtle flavor notes, and because of that, they usually preferred the samples that they didn't taste first.
Unfortunately, these chocolate shops are not common, and therefore not convenient for most people. Not to worry, you can also find high quality chocolate online. The best dark chocolates are made entirely from the cacao bean and don't contain the ingredient soy lecithin (eg. chocolate by la Maison du Chocolat).
However, you can still get reasonably good inexpensive dark chocolate, most of which does contain soy lecithin.
Good, inexpensive, and easy to find dark chocolate bars are made in a wide range of cacao contents by Lindt and Ghirardelli. Anything with sugar as the first ingredient is obviously less than 50% cacao. Stronger chocolates will have their percentages displayed on the front.
PS - We have an entire section of our fridge dedicated to a variety of dark chocolate. (Yes, that's all chocolate in the back, too.)
PS again - Ideally, chocolate should be stored and eaten at standard room temperature. However, we live in LA and don't have air conditioning, so the fridge is the next best place for our chocolate. If it gets too warm or too cold, it can "bloom," which means the fat or the sugar separates from the chocolate. This makes it look funny (slight white coating) and sometimes makes it taste stale or changes its texture. Chocolate is also made to be eaten at room temperature. Tastebuds react more intensely to warmer temperatures, therefore enhancing all flavors.More questions on Dark Chocolate: