The site is about discovery and we find that people are more excited to stretch just beyond the genre they chose than they are to get only the songs that narrowly fit the exact description. Most peoples' complaints about Pandora are that it's too narrow and plays the same music too much. We will often put a song that has ambient (or funk, R&B) elements into the channel, even if it's not straight ambient, and the rating of the song in that channel is still strong.