Boards
People you know who look like people in bands, consequently putting you off the bands in question...
OK, that was extremely clumsily phrased, but you know what I mean?
There was an extremely creepy guy in my halls of residence, who was obsessed with 80s raincoat rock. After he dropped out in the middle of the spring term, my housemates and I went to the local student pub; the video jukebox started up "The Cutter" by Echo and the Bunnymen, and we look up at the screen and see the face of our ex-housemate (who resembled Ian McCullogh to an almost terrifying degree) staring back down at us. We were all so scared we had to leave the pub, and I've never listened to Echo since.
Similarly, my ex-girlfriend is currently going out with someone who looks like Colin Meloy, so I can't listen to the Decemberists anymore...