Discover weekly is Spotify's key to that sweet payola, and it really shows. You can't remove songs from the weekly recommendation, and somehow it repeatedly gives you well-marketed artists completely outside your listening preferences.
Once I realized I just needed to give its recommendation engine more fuel to work with and started liking/adding things I actually wanted to listen to, it went right back to giving me cool stuff with loads of obscure artists I'd never heard before but liked a lot. (It really only took me about two weeks to right the ship).
Spotify's recommendation algos are excellent.
Edit: And it almost always is something I really love. That playlist is the killer feature on Spotify for me at the moment.