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.
Another folk/americana fan here, and I get contemporary pop music ads between my tracks on Spotify, and there's nothing more annoying than autotuned screeching between my Bob Dylan and Gillian Welch.
However instead of buying premium, I just use Spotify for discovery. If I like something I just get the album off iTunes, Amazon or Bandcamp. I find myself spending less per year than if I had subscribed to Spotify, _and_ I get to keep my music.
Perhaps this was intentional :-)