I usually assume that if I find a clone recipe of a certain beer, it is just a "best guess" developed by a fellow homebrewer who also likes that beer. So, considering the fact that the recipe is not exact, coupled with all of the other process variables that may affect the outcome, the likelihood is pretty low that the beer will actually taste like a bona fide "copy" of the original.
And that's just fine with me. What I do end up with is a beer that is probably pretty good, in the same vein as the original, yet something that I can say I made myself. From there, I may choose to alter some aspects of the recipe and make it more my own. I guess what I'm saying is, the real value of clone recipes for me is that they provide a reference point of roughly what the result will be like, without having to go through the 7-8 hour process and weeks of waiting to try a sample.
Another thing is, sometimes I don't want to outright copy a certain commercial beer, but rather, I want to extract a certain trait from it (aroma, flavor note, etc.). A good clone recipe can help pull back the curtain so I can get an idea of how to achieve a certain desirable trait in a beer of my own, with less trial and error.