Take a story's temperature by studying its tone. Is it hopeful? Cynical? Snarky? Playful?
Kesey is clearly sympathetic to the patients on the ward. His portrayal of the patients shows their humanity and their dignity, as well as their ability to perceive the truth of a situation despite their frequent inability to comprehend reality. Kesey’s portrayal of the staff indicates how the very position they’re put in corrupts them.