Roasted duck carcass – what is this dish called

In southwest of France, we serve confit with "pommes sarladaises", which are more or less fries cooked in duck fat in a pan. There is also garlic and parsley.

You can use confit in "cassoulet" as well. This is something like chili con carne with white beans instead of red ones, onion, carrot, tomato, garlic (and many other secrets which change from home to home).

EDIT: A variant of "pommes de terre sarladaises" includes mushrooms, in particular "cèpes" (Boletus edulis) together with potatoes.

Assuming you didn't do some kind of "flavor injection" treatment, there is absolutely no reason why one part of a bird would taste radically different from another. I'm going to go with "Bad Duck."

Cooking the bird slowly seriously reduces the possibility of a "hot spot" causing some kind of local taste variance. Breast meat will become overdone at the point where dark meat is still tasty, but that wouldn't explain smell or taste, and unpleasant smells are almost always related to bacterial issues.

If it was discolored, it could have been local bruising, which would cause some taste issues, but, again, wouldn't explain the smell.