Yes, and that just reinforces what I said. Free software done by pros is, mostly, done to professional standards, that done by amateurs is mostly done to amateurish standards.
What defines a professional or amateur, though? If you define a professional as someone that contributes to software as part of their paid work (and an amateur as anyone else), then Linux and GCC were both begun by amateurs, and are now maintained partly by professionals. Likewise, many projects are begun by professionals and receive contributions from amateurs.
