If something is done saltily, it is done in a way that is a little bit mean or bitter.
The word saltily can make people think of someone being a little bit rude or unpleasant.
Examples:
She replied saltily to his question.
He spoke saltily about the new rules.
The old man looked at the kids saltily.
The cat looked at the dog saltily.
She saltily refused to help him.
He saltily told her to go away.