The main reason I bought Spotify premium (other than access to the full mobile platform) was to ditch the ads. I don't mind ads so much, but Spotify ads are particularly annoying. I seemed to get a lot of ads from fledgling hiphop artists, including extended samples of their songs, which was really disruptive and unpleasant when listening to folk/americana. After one two many focus sessions were ruined by obnoxious ads, I went ahead and bought premium.

Perhaps this was intentional :-)