The problem is that people are using two totally different methods of comparison here. I've personally always found it a bit silly when someone says things like "there is no such thing as an NC that tastes anything at all like a CC." While I dont' think statements like that are true in one sense, I've come to understand that they are true in another sense. People are talking about two different things.
Similar Flavors:
While it's not likely that you'll find a one-to-one comparison for anything, what you will find is that certain flavors/tastes/notes are shared between some CCs and some NCs.
It's like this: If you read some CC reviews--just here on BOTL--then read some NC reviews, you might find some of these reviews strikingly similar. They will describe things like wood, cream, cocoa, etc. etc. In fact, you might have two cigars that are described almost exactly the same, with one of them being from Havana and the other from, say, Nicaragua.
But in the above case, that does not necessarily mean those two cigars "taste the same," or even that they taste alike! You could give someone two cigars and have them describe those sticks on paper and they would sound very similar. But if you asked that guy if they tasted similar, he might say "Not at all." But if they have similar flavors, how can they not taste similar? That's an issue of semantics, and is the main reason why people disagree on this whole issue.
The reason every cigar from say Nicaragua is different is because the way all the flavors and characteristics combine will be unique in each case. So although all Nicaraguan cigars are different, you will probably still be able to guess it's a Nicaraguan cigar if you've smoked enough of them to be familiar with the specific qualities of Nicaraguan tobacco.
Cuban tobacco too has unique flavors and characteristics that make it as different from Nicaraguan as Nicaraguan is from Dominican. Though sometimes you will find an NC that tastes a lot like Cuban tobacco--I mean the tobacco itself--it's very uncommon. What is more common is that you'll find specific flavors in one that you can also find in the other.
Overall Similarity:
The more you smoke CCs, the less overall similarity you'll likely see between them and NCs. It's rare that you find an NC that really fools you into thinking it's a CC, and vise versa. It does happen, even to guys who've been smoking for many years, just not that often. Again, it's not the specific flavors like "cedar" or "chocolate" we're talking about here, it's the overall final picture. This takes into account the unique qualities of tobacco from the island--flavor, texture, impact on the palate, style of complexity, etc. Some of these things are a bit harder to describe, but the end result is that even if a particular CC and NC look similar on paper, the smoking experience itself (for the seasoned smoker) will usually be noticeably different.
Here's an example:
I love Bolivars. To me they are completely unique among cigars, and just plain wonderful. There is nothing I've ever had that tasted like a Bolivar. But the first time I smoked a Bolivar, I noticed a specific flavor in there that reminded me of another cigar, the Perdomo ESV '91. It's a unique combo of pepper with cream that melds together to form something really delicious to me.
Having since then smoked quite a few more of the Perdomo ESVs and a few more Bolivars, I do indeed still find that similar flavor. I've never found it in anything else, but it's in the ESV. Now, I'd never say "The Perdomo ESV tastes like a CC Bolivar," because it doesn't ... at least not in the overall picture. But I have said "The Perdomo ESV has a certain flavor that reminds me a lot of a CC Bolivar" because that is true. In one sense they are similar, in the overall sense they are not.