Your point is well taken, Didge, but you may have overlooked one factor. If the song is in your head all the time, you may get so used to it that you no longer hear it, just as you would get used to a persistent odor so that you no longer smell it. If that is the case, I would much prefer getting used to a pleasant song than a foul one, as would be the case with pleasant and foul odors. (response to foul odor)->