Why does the author continually mention the redness of Mr. Ewell's complexion?

This is a fun question, I think. As a reader, I enjoy speculating about odd details in a text.

There might be at least two reasons that the Harper Lee's novel To Kill a Mockingbird makes repeated reference to Mr. Ewell's ruddy complexion.

1. Mr. Ewell doesn't often bathe, and Lee's novel seems to be taking part in that long-held belief that cleanliness is next to godliness. Ewell is not a good or godly man, so it makes sense that he might be shown to be physically dirty, too. When he does finally scrub off the dirt for the trial, his poor skin is so irritated that it's red.

2. The ruddy complexion fits with the narrator's comparison between Ewell and a little bantam rooster, a feisty self-important little beast that struts around and thinks much too highly of itself. The chickens that pick out in the Ewell front yard are much like the Ewells themselves, so it works well in the narrative that their boss would be a little rooster.