I've come across several bands that Spotify has decided are similar enough to play on the Radio together. Somehow, the player thinks I'll like to hear Nickelback on a station centered around Hollywood Undead, for example.
And even after giving half a dozen or so of the band's songs a "thumbs down", Spotify will keep serving up more of the same. It interferes with the very notion of a station that I can't say "get this band gone" and disrupts the flow of listening to music.
Please, either get the system to recognize a bias against a band quicker, or give us an explicit "nothing from this band" option.