Take a story's temperature by studying its tone. Is it hopeful? Cynical? Snarky? Playful?
Judgmental, Playful, Comic
We get the feeling throughout that O'Connor thinks her characters could be much better people than they are, especially Hulga and Mrs. Hopewell. Yet she puts forth this attitude in a playful way that encourages the reader to laugh at the characters and the scenarios.
We see the judgmental aspect of the tone most whenever the topic of "good country people" arises. For example, we learn that Mrs. Hopewell's "reason for […] keeping [the Freemans] for so long was that they were not trash. They were good country people" (3). Something in the tone suggests that O'Connor doesn't think much of someone who thinks of some human beings as "trash," or who believes herself to be in a position to decide who fits into this category and who does not.
While every line seems laced with judgment, the story is infinitely playful and comic. Since she names a character Manley Pointer and gives him a Bible hollowed out and filled with booze, cards, and condoms, some readers might be surprised to learn that O'Connor was a devoutly religious woman. She definitely shows that she's not afraid to write what seems irreverent, or to have a good time while getting her point across.