Rose Rosetree, author of Aura Reading Through All Your Senses dispels a lot of myths about what aura reading is and is not.
First, it is not something that you necessarily born with. According to her, almost anyone can learn to read an aura. She gives several techniques on how to do just that.
Second, aura reading is not always done with "second sight." Auras may be read in other ways -- through any of the senses engaged in a extrasensory way (yep, according to Rosetree, you can 'taste' an aura). For us empaths, we already read auras, either by sensing someone's physical state through our own bodies (like when we "catch" someone else's headache), or by feeling their emotions.
Third, the colors that one "sees" are not the same ones that every other gifted persons sees, and the colors do not all mean the same thing. I think one of the most important thing that Rosetree does is to take aura reading and aura readers off their spiritual pedestal and teaches you how to build your own internal dictionary of aura meanings. Hats off to her for that!