Take a story's temperature by studying its tone. Is it hopeful? Cynical? Snarky? Playful?
Reading I Am the Cheese, we can tell that the narrators are just as unsettled as we are. It's hard to put our finger on why everything feels so strange, but it's all made clearer when we look at the no-nonsense, tell-it-like-it-is side of things. Our narrators (and hence, the author) certainly aren't wearing rose-colored glasses. Everything is told exactly the way it happens, and the narrators don't try to put a fancy spin on anything. This makes sense, given that a lot of the story is told through Adam's eyes; what we're getting is pure observation and very little analysis. The analysis is done by us as readers – we weave the pieces together as we go. (Way to make it tougher on us, Cormier!)