Authors should always work hard to avoid offending a reader. When self editing, important areas to look for are narratives that smack of author intrusion. Readers can easily spot an author's opinion peeking through the pages of a manuscript. Sometimes this narrative is, sadly, intentional. An author has a strong socio, economic, or political stance, and he wants the world to know it. This is the ultimate form of "telling" and not "showing." The author's opinion is better shown through the dialogue, action, and thoughts of a character with careful attention paid to offering an alternative viewpoint. In other words, let the reader decide.
When the narrative intrusion is unintentional, the cause for the misunderstanding reached by the reader is usually due to the fact that the author has not set the stage for the character's viewpoint. Simple issues can become a maelstrom if author intrusion is considered the source of the belief. Hotbed topics such as race, religion, even opinions about what area of the United States you reside, can anger a reader if not presented through the character's viewpoint.
For example: If an author simply states in narrative that Southerners are opinionated, a Northern reader might agree, but a Southerner reader is likely to say, "What? I'm not opinionated, and that's a fact!" But if the author lays the groundwork for her character, MaryLou, who has never been out of her small Southern hometown, who is now in New York City alongside her editor, a New York City native named Giovanni, MaryLou's opinionated personality can be shown: "A person should always say thank you when someone holds the door open for them. In the South such rudeness is unheard of." Giovanni would then counter her by leaning close to her ear, "And where you come from, MaryLou, the door is usually held open for one or two persons. Holding a door open in New York City is like opening the floodgates. Who has time for all the thank yous. They are implied." The key, unlike the reply above that I gave to my fictional Southerner reader, is to offer a balance. And who knows, MaryLou may learn to love New York City, and Giovanni, might want to move to the South where he doesn't have to hold the door open for so long.
Perusing a manuscript for personal opinions given through narrative intrusion will prevent an author from making a bad impression upon an agent or editor.
Until next time, happy editing.