"DECADENT" is a two-faced beauty of a word. In common use, it describes things which are grand, opulent, and excessive. Ham-fisted, two-pound chocolate desserts at corporate-designed, pandering chain restaurants are "Decadent™," and caviar and champagne are the symbols of a night of decadent luxury. But there in plain sight, on the page of your friendly Oxford English Dictionary, is the root and true original spirit of the word: decay. Things which are decadent are degenerate, falling into inferior states, out at the elbow and long in the tooth. They are fermenting, rotting, spoiling, and moldering. If you immediately made the connection between those latter qualities and the foods you love, you may have a bit of a decadent tooth.
What is the best and most satisfying eating, if not decadent eating? From the moment something ceases to live, it decays; to cook, then, is to accelerate, retard, and arrest decay. It is the art of locating a premium in the spectrum of edibility.
For nearly all of the history of our animal kingdom, we have not had sanitation, refrigeration, or wet-haired little men with clipboards running their fingers along prep counters. Our brains, though, must have developed a love of all digestible flavors—right up to the point where they became strong enough to kill us—because otherwise that would mean waste, and pre-agrarian death by starvation. So, we have an affinity for soured milk, the byproducts of yeast, and creatures that dried in the crooks of trees. As a species of growing intelligence and resources, we eventually cut our losses and forbade some of these things to one another, for the safety of the group—but at the loss of some pleasures.
Here is a reminder to seek those things out and consider why they thrill us. We explore moldy cheeses, disturbing animal anatomy, fermented drink, and tales of grand combinations thereof. This is some of the greatest eating, and "decadent" is just the corrupt little word for it.