Over at Ionarts, Mr. Downey has a discussion of singers who don't know much about music. My favorite quote:
“Fine voices are like fine instruments, because people will go to extraordinary lengths to hear them played. However, the best instruments can be given to the most skilled and intelligent musicians, while the voices end up with whoever has them and cannot be transferred.”
The problem is that you have to distrust anyone who can sound good at their instrument without actually learning anything about music. Singers are the most prone to this problem obviously. A singer can sound great without learning anything about music. A great singer has been given a gift, and it is a shame when they treat it as such. I don't mean to imply that there isn't a craft to singing, or that singers can't know a lot about music and be great musicians. Actually, the fact that there is a lot of craft and knowledge that can go into singing makes it a greater tragedy when great voices don't study it. Does any of this matter when you are listening? No. But it can drive you insane when you are playing with them.
Just to show you that I can be fair, the other instrument that is most prone to this disease is the guitar. With the invention of tablature, a guitarist can sound fantastic and not even know the name of a single note. I was at a bar once with a moderately well known singer songwriter who seemed to be almost proud of the fact that he didn't know the names of any of the chords he played.
I just find it amazing that in music you can get away without really knowing anything about the discipline. I don't know if this is comes from an idolization of people like Charlie Parker, or a remnant of punk music, but it drives me insane. We love natural ability in music, and deify it to the point where we want to leave it untouched by the ravages of knowledge. Sometimes I think that authenticity is a quality valued to highly among musicians.