aftertaste [af-ter-teyst, ahf-] noun
A pleasant or unpleasant flavor that lingers in mouth after swallowing a food or beverage. Even though the food is no longer there, the lasting taste is very much a part of the experience. When used colloquially, it is often to describe an unpleasant flavor. In the food realm, it can mean either.
Some foods, like dark chocolate, have a very long aftertaste, while others, such as a simple sugar cookie, might fade from the palate more quickly. Neither is better than the other, it is just a way to describe a gustatory experience.