"Many of us have had the experience of living in some local pocket of human society--some particular school, college, regiment or profession where the tone was bad. And inside that pocket certain actions were regarded as merely normal ('Everyone does it') and certain others as impracticably virtuous and Quixotic. But when we emerged from that bad society we made the horrible discovery that in the outer world our 'normal' was the kind of thing that no decent person ever dreamed of doing, and our 'Quixotic' was taken for granted as the minimum standard of decency. What had seemed to us morbid and fantastic scruples so long as we were in the 'pocket' now turned out to be the only moments of sanity we there enjoyed."
C.S. Lewis, from "Mere Christianity" - emphasis mine; this kept me sane in several such places.
_________________
"I believe you find life such a problem because you think there are the good people and the bad people," said the man. "You're wrong, of course. There are, always and only, the bad people, but some of them are on opposite sides."
-- Terry Pratchett, Guards! Guards!