Take a story's temperature by studying its tone. Is it hopeful? Cynical? Snarky? Playful?
Observant, Thoughtful, Earnest, Critical
Even though there are plenty of dry descriptions and blunt observations, they're often written in a tone that gives surprisingly poignant moments of observation about humanity. For example, when Tom and Polly Ann find the chests and drive to Billy-Bob's in the middle of the night, Tom puts his horse, Drew, in Billy-Bob's stable:
Tom found some oats in a bin, but they smelled stale and sour, so the old horse would have to go hungry until he got home. Tom told [Drew] he was sorry and left him standing there, probably philosophizing on the unreasonableness of people. (52.16)
This is actually a pretty funny quote. Think a 1900s version of a meme with a dog or cat grumbling about their owners.
But an old horse isn't the only character to get his philosophy on. Tom often gets "to thinking how queer some men could get to be" (49.8). Based on quotes like these, the text actually seems fascinated with people and their strange habits. It gives the idea that many fit into a certain "type," but everyone is also a little strange, or has their own little quirks.
These thoughtful asides can also take on sad or critical tones. For example, there's a sad sensitivity in the following passage of Birdy opening his Christmas present from Tom:
He folded the paper carefully and put it to one side for Polly Ann to use again if she was so minded, but the wool he wound in little circles just as carefully and put them in his pocket. Tom wondered what he planned to do with them but didn't want to ask. Early in March when he went to visit with Birdy one Sunday, he found that Birdy had made decorative nots out of each one and hung one in each of his two kitchen windows. There didn't seem any point in saying anything about them then, either. (18.9)
Birdy is an extremely capable worker, a resourceful man, and a guide for Tom, but he is also alone, with no family and not much money. His careful saving of the wool from his Christmas gift, perhaps to add a domestic touch to his kitchen or to remind him of the gift, tugs at the heartstrings.
As for the passages that are critical, those often come to show the difference between Tom's industriousness and the lazy, gluttonous ways of other men.
Overall, the tone comes across as one that carefully observes and reports human nature. You sometimes have to read carefully to find these gems amid the dry descriptions, but that seems to be part of the point: a close reader, like a close observer of the world, will find all kinds of interesting things.