Dude, what are you talking about? I have loads of shoes where, if you really look, you can plainly see slight differences between the left and right shoes. And I have multiples of many shoes where you can see differences between every shoe in the set. If I came over to your house, I guarantee I could show you little differences in your shoes, too. But that's the key: Most of them are small enough that you really have to look at them with an eye for spotting these differences to really notice.
Similarly, most of the differences people are pointing out on pairs in this thread are pretty minor, and they're just part of the random aspect of the large amount of materials Nike sources for this stuff. That's why some pairs have more tumble than others, why some EP looks thin and some looks thick, etc etc. We discuss them for fun and entertainment, really, but the vast majority of what I've seen in here doesn't really qualify as something being "wrong" with the shoes.