Walter Cunningham appears in school as a somewhat ignorant but proud young man, unwilling to accept the charity of the teacher but also clearly willing to try his hardest and polite to a fault.
When Walter comes over to the Finch household for dinner, Scout does learn a few things. First, it strikes her that Atticus is so deferential to their guest, somehow she thinks that the Cunninghams are different, that somehow they should be treated differently. She is particularly incensed when Walter puts syrup all over most of his dinner, shouting about it until Calpurnia drags her out to the kitchen to straighten her out. Scout learns that while there is a distinction between the Finches and the Ewells, it is because of the Ewell's mean and nasty behavior, not their lack of material things.
Walter and the rest of the Cunninghams are working hard and are proud of the fact that they do their best despite not having much. Atticus makes it clear that they are to be respected as a well-to-do family with the same behavior.