Maybe it's the reverse, and people who are used to artificial sweeteners have trouble telling whether something's real sugar? I've never been a diet soda drinker, so maybe that's why I can detect it easily.
Or maybe I missed my calling as a soda super-taster. I can also tell several major brands apart by smell; back when I was a major soda drinker I'm 100% sure I could have labeled at least four Dr. Pepper knock-offs in a blind taste test; and find the "Pepsi challenge" literally incredible, as in I can't believe the outcome is real because they're so obviously different.
NB: I'm referring to Coke Zero, not Diet Coke
(By the way, I know quite a few people who, according to their words, actually prefer the taste of Coca-Cola Zero. I personally cannot say that I like one more than the other, even though the taste is obviously different. So I'm surprised by how it is almost unanimously assumed in this thread to be bad-tasting.)
I'm one of the people who finds Diet Coke and Coke Zero terrible-tasting. Do you enjoy the taste of any other artificially sweetened drinks, out of curiosity? I wonder if some people just have a trait that makes any non-sugar sweeteners taste awful to them.
Aspartame, stevia, monk fruit, and sucralose all taste truly gross to me. Like, gross in a weird, chemical-y way nothing else I've ever tasted does. Very distinctly, particularly, and strangely gross.
All real sugars taste great to me, though. If it weren't so unhealthy, I'd probably consume lots of sugary foods almost every day.
Well, first off, I don't like Coca-Cola that much for that matter (which I assume you mean by "Coke"). I just find both Coca-Cola and Coca-Cola Zero perfectly drinkable and occasionally I feel like drinking one or the other. I never really drink "Diet Coke", since while "Coke" and "Coke Zero" are just 2 clearly distinct drinks, "Diet Coke" is something weirdly in between. Not gross, but meaningless and less enjoyable than any of them.
That being said, Coca-Cola is one of the least interesting and most bland colas out there. I would prefer "Fever-Tree's Cola", or "Jarritos Mexican Cola" or half a dozen of another colas over the one you probably mean by "Coke". So it's kinda silly to me to compare another drink (Coca-Cola Zero) to it as if it was some Holy-Grail of colas. It's just a mediocre drink, not amazing, not disgusting. And so is Coca-Cola Zero.
I cannot right now remember vividly enough the tastes of other drinks that might have been artificially sweetened, so I cannot answer your question directly. I don't like the taste of aspartame on its own, I don't use it at home, but I don't remember which off-the-shelf drinks contain it. Sucralose is better, protein powders are often sweetened by it, but it all depends on how much of it do they contain. I specifically checked right now 2 brands of which I remember one being horribly sweet, and the other quite nice: both have just sucralose as a sweetener, but they taste vastly different. On the other hand, Nocco drinks also are sucralose, they aren't too sweet, but I don't find them very pleasant to drink.
I cannot remember how stevia tastes (I guess I must have tasted it, but I cannot remember when or where), and it's possibly the first time I hear of "monk fruit". I'll try them out, I guess.
So, TL;DR: the particular sweetener doesn't define the taste of the whole drink, it really depends if I will like it or not.
To me, artificial sweeteners instantly overpower the taste of anything I drink. I'm not a big fan of (regular) Coca-Cola, either, but no matter the drink, artificial sweeteners just ruin the whole experience. Compared to anything with an artificial sweetener, Coca-Cola might as well be the best thing ever.
It's all the after taste, for me. If I sip a diet soda, there's about one full second when I can't tell the difference—then I really can, and the unpleasant-to-me flavor lingers, quite strong, for minutes. Tastes like... I dunno, like I chewed up and swallowed a mild licorice with a thin coating of something that's definitely not food. Maybe some kind of plastic or household cleaning product.
The only cola I've ever had where the diet version that has been close to fooling me was RC Cola. I think overall the colas with a stronger caramel taste like RC and Dr Pepper tends to fare better, because there are other taste notes that help obscure the lack of sugar.
If I was going to switch to a diet soda, Coke Zero would certainly not be it.
(Of course, Coke Zero seems to no longer be a thing at least in Australia, we now have No Sugar Coke which is different and IMO not quite as nice but that's what we get.)
I've never had any drink with an artificial sweetener that I've enjoyed the taste of, and I've tried a ton of different ones. I now just choose between sugary drinks or water based on if I want to treat myself or not.
I'm someone who likes good food and can usually identify most of the spices and ingredients in a meal by taste and smell, but for whatever reason, to me, Coke Zero is almost identical to the real deal.
I'm a bit surprised by the reaction here because I had incidentally just talked about it with some co-workers the other day and we were all on the same page about the minimal taste difference.
I have actually tested this blind and from memory at least ten of the thirty or so people asked could identify it (artificial sweetener, in multiple contexts) by taste. Far from nearly impossible.