Miss Strangeworth prides herself on pointing out faults in others. She is an elitist in this way. She thinks she has the moral authority to judge others and therefore, she thinks she is doing her part to eradicate evil in her town. However, the irony is that she is the one spreading misfortune and mistrust among the other citizens and therefore, she is the one creating more possibilities for people to be evil to one another.
Her name is "Strangeworth." We might say that it is "strange" that she thinks there is value and worth to the work she does with her letters. In other words, she thinks she is doing something good, but the reader (and her fellow citizens) would argue that it is strange to consider these letters "worthy" of any praise.
She also has two identities. She is amiable and friendly with people in person. But when she goes home, she becomes a malicious judge of those same people. "Strangeworth" nearly sounds like "stranger" and she is a stranger to those people. They don't know her real personality, her real feelings.
The poet William Wordsworth has a name that is appropriate. He is a poet who's name suggests that "words" are "worth" something. Miss Strangeworth's "worth" is strange. Consider some synonyms of the word "strange" and how they might apply to Miss Strangeworth: deviating, unfamiliar, unknown, outlandish, aberrant.