The best way to know if your leftover stuffing is still edible is by using your sense of smell and sight.  Take a whiff if you take out the stuffing from the freezer and can’t tell by looking at it if it is edible or gone bad. The spoiled stuffing releases a sour smell after it has gone bad. It is because of the ingredients that are used in preparing the stuffing. If you notice a sour or off smell coming from the frozen stuffing, discard it immediately. Another way to tell if your stuffing has gone bad is by looking at it. If your stuffing looks odd with off-color, you must smell it to ensure it is still good and edible. If you see mold growth or discoloration on the surface, throw it immediately. It is a sure sign of spoilage.