Expert radio programmers.
I heard this amusing, and telling, story yesterday on our local non-commercial radio station. They're in the middle of a fund drive and were discussing that none of the money goes to consultants; the station personnel can figure out what to play by themselves.
Anyway, a few years ago one of the DJ's was working at a commercial, but progressive, rock station. One day he was called in to a conference and introduced to a consultant, who handed him three lists, each with 750-1000 songs. He was told he was only allowed to play songs that appear on all three lists. Well, after considerable complaints, they started to go through the lists. When they got to Eric Clapton, the consultant said, "See, here's "Layla" from his Unplugged album. You have to play that because it's on all three lists."
The DJ said, "If I'm going to play "Layla", I'm playing the long version by Derek and the Dominoes."
To which the consultant replied, "Oh come on! Don't you think your audience would rather hear a guy like Eric Clapton play his own music, rather than some crappy little band named Derek and The Dominoes?"