Wheras, I'm a garden variety reader, playing mostly the given chords, I make changes, as well as adding chords. Fake books are only a rough skeletal quide at best. For example, I might change a G7 chord to G7AUG for added tension. The big boys come up with chords that would knock your socks off. There is a chord for every movement of the left hand and ear players could well be doing the same thing, except they have no given name for it.
Bernie