This is an offshoot of “showing vs. telling.”
When you use an adverb you are “telling.”
“Telling” is a less immersive reading experience, and often conveys less meaning than describing the emotional beat of the scene.
As an example:
“Great,” he said sarcastically.
James’ mouth twitched at my news, and he shifted his stance to lean against the bookcase. But instead of relaxing as his body suggested, his eyes narrowed as he studied my face. What was he trying to parse? Did he suspect I lied to him?
The corners of his mouth curled upward and I could see the skepticism in his eyes. He pulled a cigarette from his inside suit pocket knowing I despised the things, lit it, turned his head away, and drew in, then let out a long breath.
“Great,” he said.
What did you learn about the characters in this little scene? Do you not sense of tension between the two? Don’t you just feel the sarcasm in his one-word utterance?
When you use an adverb you miss out on a storytelling opportunity that broadens the emotional content of the scene.
You use an adverb when the pacing of a scene is quick and you don’t want to bog it down with too many words. Otherwise, it’s your duty as a writer to flesh out that scene.
Storytelling is a marathon, not a sprint.