Anyway I don't like to use right/wrong and good/bad: who stands as judge? Where is this so-called objective judgment? It does not even exist in science: the scientist who studies sub-atomic phenomena modifies them (with detection instruments) the moment he studies them. Objectivity is an illusion.
I would rather say that so-called crazy people are considered "wrong", not the opposite.
Then I would not use common sense to measure a person's sanity (not normality)...