“It can be tempting to try to be more descriptive with your dialogue tags” she said, enigmatically.
“But that comes at a price,” he blurted.
Dialogue tags are the way that a writer conveys that a character is saying something — like “enigmatically” or “blurted” above. The worst offender I’ve seen is unquestionably “ejaculated,” which forces quite a different frame of mind upon the reader. J.K. Rowling seems to be especially fond of adverbs — Harry and Ron and Co are always saying things “darkly.”
The beauty of “said” and said alone is that it’s mostly invisible. It functions in a way that’s close to punctuation. Like the stagehands in black who you can barely make out between scenes in a play. The reader just reads it and reads on. When you get a tag with a stronger flavor, it may seem comforting because you’re being extra descriptive, or you’re doing more, but ultimately, you risk evicting the reader from an important moment.
An exception: if the dialogue is being delivered in a meaningfully different way, it’s still valuable to be able to say “she whispered” or “she shouted.” Using those once in a while makes sense but when paragraphs become full of “commented” “responded” “confided” “announced” “retorted” it can have the effect of making the text feel like a text. Ideally, you want your story to feel natural and immersive. At its best, the reader should be submerged in it. A sense that Margaret Atwood captures in the passage below.
“When you are in the middle of a story it isn’t a story at all, but only a confusion; a dark roaring, a blindness, a wreckage of shattered glass and splintered wood; like a house in a whirlwind, or else a boat crushed by the icebergs or swept over the rapids, and all aboard powerless to stop it. It’s only afterwards that it becomes anything like a story at all. When you are telling it, to yourself or to someone else.”