Robin's answer hinges on "all else being equal." That condition can tie up a lot of loose ends, it smooths over plenty of rough patches. But those ends unravel pretty quickly once you start to consider all the ways in which everything else is inherently unequal. I happen to think the dust speck is a 0 on the disutility meter, myself, and 3^^^3*0 disutilities = 0 disutility.