They probably wouldn't give marks for sustaining notes into harmonic feedback, but nor should they, because that's an individual touch that shouldn't be learnt from a book... but there are some things that all musicians really should know, like a good understanding of theory and harmony, sightreading, aural skills, etc, and the guitar is the probably only popular instrument where none of these are usually taught!
Playing music is simply far more enjoyable when you know all this stuff, and props to Joe for making the decision to learn it.
