In general there is a distinct taste difference between tobacco from Cuba, Honduras, the DR, etc. etc. That is how you can tell the difference in most cases, if you have experienced enough of the different countries tobacco. Now, for counterfeits made with Havana leaf, the difference is not always in the taste, as much as the cigars construction and what part of the plant the leaf comes from. Often times a counterfeit from Cuba will include clippings, stems or even non-tobacco plant or material.
Then there is the blend difference, which is harder to discern if you are not experienced with the different brands. This is not only the case for Cuban cigars, but also the fake Padrons, Opus, etc.
I don't think you have to be bale to taste all the different nuiances of each individual country's leaf to recognize that there is a difference in taste. That is why you know what you like and what you don't like. If you couldn't taste the difference, then it wouldn't matter what cigar you were smoking. They would all taste the same. Now, you may not associate the taste with a certain country's leaf, but that is because you haven't conditioned yourself to do so.
Now onto the source issues raised. How do we know certain sources are selling legit cigars?? Well, to be honest, you don't unless you do your research. This is based on opinions of others, research into the vendor's actual business and meeting the vendor or visiting the operations. That's why we tell people not to jump right into something both feet first. There are vendors out there that seem legit and then they slip some counterfeits into shipments down the line. It happens and that's why you will see these people called out. It may not happen on all the boards, but it does happen. Most of the "FOG's" do not mind giving out opinions of different vendors, but we would prefer it is done in the appropriate manner, privately. It has nothing to do with our being superior beings. It's a respect issue with the vendors. Some of the people we deal with do not advertise their business. All one has to do is ask. I personally have a rule that I will not refer a person if I have not met them in person. That is just a rule I made for myself as it used to be the only way to get "in".
As for the re-banding over shipping intact.. well, that is a vendors choice based on what they have seen happen in their shipping. You will notice that those who ship intact, in general, do not guarantee shipment.