I think Pandora had the right idea, but a thumbs up gave an equal thumbs up to all aspects of a song even if you really liked a song despite some aspects of it.

They needed an interface for songs that you had liked that looked like an equalizer or maybe a color wheel and would let you give higher ratings certain aspects of a song and lower ratings to another.

Instead, if you gave a thumbs up to an acoustic version of a song that just happened to be recorded as part of the live event or concert (I'm looking at you Layla) then every one of your channels would be filled with nothing but shitty ass live versions of everything.