I have heard that many elite virtuosi are not good teachers for beginners, because manual dexterity comes so effortlessly to them that they never analyze it sufficiently to teach it.
And further, that some virtuosi play with bad technique, and overcome it with the brute force of their raw talent, thus having a second reason for not teaching beginners. To get on or off this list see list information at http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html
