If aesthetics is the argument, then I think one would also need to object to creating any trails in the wilderness. Semi-permanently scarring the landscape to make a trail is much worse than creating a small pile of rocks that does not damage the terrain nor impact the ecosystem. Ed, I am guessing you do not object to the trail systems that exist in our local mountians or the Sierra Nevada, and which it sounds like you regularly use? I completely agree that painting rocks or leaving behind ribbons/wands is not acceptable. And I would not object to scattering a cairn that is placed in the middle of an obvious man-made trail (especially if it impeeds hiking on the trail). But if you knock down a rock cairn someone else may have made in an off-trail area or an area where the trail is difficult to navigate, then you are needlessly increasing the risk someone might get lost and subsequently require a rescue. If you don’t trust the cairns created by somone else, don’t use them to navigate, and I think it is safe to assume everyone else navigates via previously made cairns at their own risk.