Memetic elements to the music I enjoy
Pandora has decided, after much deliberation, that I prefer music including certain particular elements:
a Romantic-Era style
minor key tonality
a passionate atmosphere
an emotional aesthetic
a well-known composer
a bittersweet sentiment
Two of the stations I have created eventually settled almost entirely on songs including most or all of these elements.
It's interesting, particularly since Pandora selects music based on these almost genetic elements, rather than a typical coorelation engine. It's akin to a political system where one votes "on the issues, not on the people."