Overuse at best is needless clutter; at worst, it creates the impression that the characters are overacting, emoting like silent film stars. Still, an adverb can be exactly what a sentence needs. They can add important intonation to dialogue, or subtly convey information.

No, when you love someone you spend hours and hours with them, and even the mightiest forces in the netherworld could not say whether the hours you spend increase your love or if you simply spend more hours with someone as your love increases.

He thought she knew what he meant, but the biggest mistake you can make is thinking they know what you mean.