We had lunch in a restaurant in Williamsburg, VA last weekend. My sister made a comment that the ceiling fan was unbalanced and was making an annoying ticking sound. I hadn't noticed it until she said something. Then it started to drive me nuts. That's all I could hear. I couldn't focus on the conversation at the table.

My fan issue is similar to what happens when your documents are riddled with formatting, grammatical, or typographical issues. Your readers get lost in the annoying noise, and they can't focus on your content.