In this season of summer travels we may be more focused than usual on following maps and heeding our various tracking devices to get where we want to go. And we sometimes may be led astray, perhaps because a street sign is hiding behind a tree, or by a poorly marked on-ramp.
Similar dangers abound as we navigate one another's sentences to reach their meaning. We sometimes think we're on our way to one destination when, oops, we see that a word we thought pointed to one direction of meaning actually leads to another. Here's a classic example: "However the enterprise may turn out in the end to have been not without its lessons."
However is a perfectly respectable way to introduce a dependent clause. But in this case, the earnest reader moves along as far as "end" and then expects the meat of the sentence, the independent clause. But no, all that's left is an infinitive phrase. The reader must then start over and mentally supply the missing comma after "however." Once it's clear that "however" is just an introductory adverb, the sentence makes sense.
Careful writers seek to avoid such awkwardnesses and confusions. The famous grammarian Henry Fowler had a term for them: false scents. The example above is one of his. He seems to have found false scents one of the more entertaining grammatical foibles: "The laying of false scent, i.e., the causing of a reader to suppose that a sentence or part of one is taking a certain course, which he afterwards finds to his confusion that it does not take, is an obvious folly...."
That it is folly is no reason that people won't do it, of course. (For more on this, see the works of Barbara Tuchman, and any number of recent chapters of American foreign policy.)
Folly may be hard to avoid in the larger sense. But I try to keep it under control in copy I'm editing. I have a mental list of words that I keep an eye on. Fowler may not have described them as false scents. But they have potential to lead readers astray.
•As can mean either "while," on one hand, or "since," in the sense of "because." In the sentence, "As he was heading into town, he offered her a ride," either meaning is plausible. If context doesn't already provide clues, it might be smart to supply them ("As he was heading into town anyway, he offered her a ride"), or to use while or since instead.
• Estimate, as a verb, can be followed by a noun ("He estimated the job") or a complete clause ("He estimated the job would take five hours" or "He estimated he could do the work in five hours"). Note the slight ambiguity in the middle example, and note how it disappears with "that" inserted: "He estimated that the job would take five hours."
• While can have the sense of "although," but I like to reserve it for situations with actual simultaneity: "While she has many critics, she has many keen supporters, too." Better to stay away from such absurdities as "While he was born in New York, his sister was born in California." This suggests either half sibs born to a bigamous father, or a mother who is awfully busy.
You may not stumble into anything quite that colorful as you write your vacation postcards. But Fowler's point is worth heeding: Beware the folly of the false scent.