Links in this essay will take you to information about the usage experts and their work. Numbers in parentheses are page references in the sources.
A dangling modifier "dangles" because there is no word that it can logically hang on to. Instead, it tries to attach itself to a nearby word and creates an absurd meaning.
When only ten years old, my grandfather took me skydiving.
Writing frantically to beat the deadline, the clock told me time was running out.
Surely the grandfather wasn't ten years old, nor was the clock doing the writing.
Why should writers avoid dangling modifiers like these? The obvious answer—that danglers cause ambiguity or seriously interfere with the writer's intended meaning—is probably wrong. As Kenneth Wilson points out, dangling modifiers "have long managed to get by in the best English and American literary company without being noticed" (122). Roy Copperud agrees:
"Dangling [modifiers] rarely confuse meaning. At the least, they cause the reader a moment of hesitation… At the worst, they create an absurd effect" (117). Fowler echoes the point: "It must be admitted that unattached participles [danglers] seldom lead to ambiguity. They just jar" (805).
Despite these admissions, Wilson, Copperud, and Fowler advise writers to avoid dangling modifiers. Most usage experts agree that the error is distracting.
The error can also be quite funny. Patricia O'Conner writes, "I've grown almost fond of . . . the dangler. It's a word or phrase . . . that's in the wrong place at the wrong time, so it ends up describing the wrong thing. Here comes one now: Strolling along the trail, Mount Rushmore came into view" (160). Though it may be a good thing to amuse readers now and again, most of us would prefer to do so intentionally. When we write a dangling modifier, the joke is at our expense.
Conclusion: Though dangling modifiers don't always cause confusion, they are worth fixing because they distract readers and risk making the writer look foolish.
Source: Hacker Handbooks (Boston: Bedford, 2013).