I don’t have pet peeves like some people. I have whole kennels of irritation.
-Whoopi Goldberg
Whoopi gets me.
Take, for example, the sentence: “They worked feverishly.”
While it’s possible that the author meant in a feverish way or in an restless manner, it’s far more likely that he should have used fervently, which means in an intense way or in an enthusiastic manner.
Of course, the better option is to drop the adverb altogether and choose a stronger verb: toil, hasten, clamber, and scramble come to mind.
The lesson to take away: words matter; choose carefully.