Well, I think there is a certain percentage of the population that just hears things differently. Some one I know tells me they hear earphones differently than me; like the Xelentos, which I love the high end, he says the treble sounds screechy; and I love the Legend X and he just hears it differently; in fact he loves the CL2, and doesn't like BA at all!
I'd say it's probably close to 100% hear things differently with earphones and all audio gear otherwise we would all own the same set of earphones, no head-fi required lol