"Terms such as mental illness and mental disorder are not precisely defined, and we doubt that they can be defined based on science alone. Values-–our opinion of the desirability of a condition-–invariably intrude on the decision whether that condition is a mental illness or merely reflects a difference with other people."

That's from the Virtuous Pedophiles FAQ, and it seems worth thinking about. I actually think most "crazy people" DO know they're crazy, because their own thoughts don't add up to a coherent whole.

But mostly we're labeled sick because we're both statistically unusual AND severely frowned upon.