Mr. Lewis grew up with Miss Strangeworth. They were in high school together, and they shared basketball games and picnics, as well as school dances, but after they graduated and he became the grocer, their relationship became more distant and formal.
Miss Strangeworth, despite their shared past, manages to be critical of Mr. Lewis while she is shopping in she store. She decides he looks very tired. Then she offers an implied criticism, expecting him to remember that she buys her tea on Tuesday. She doesn't openly criticize him but leaves him with the feeling that he failed and that she thinks he is perhaps losing his memory.
Miss Strangeworth, we find out later, also has imagined that Mr. Lewis's grandson is shoplifting, and she writes him a poison pen letter on the subject. She thinks that he
would never have imagined for a minute that his grandson might be lifting petty cash from the store register if he had not had one of Miss Strangeworth's letters.
We can see from all of the above that Miss Strangeworth views Mr. Lewis as one of her flawed neighbors, someone in need of her correction. He falls into the category, along with everyone else, of someone "lustful and evil and degraded." She watches him, just as she watches the rest of the townspeople.
Miss Strangeworth likes to think of herself as purer than her neighbors. She lacks the ability to be able to see that she is a flawed person who has repressed her anger and aggression for so long that it erupts in the form of letters meant to hurt her neighbors.