If it has a sour taste or smell, it may have bacterial spoilage and should be discarded. A chemical odor and taste may mean it’s rancid. This can happen when oxygen or microbes damage or break down the fruit’s unsaturated fat. Rancidity can result in the formation of potentially toxic compounds. Don’t eat an avocado if you think it’s rancid.
The flavor of spoiled avocados can vary, but it’s usually easy to tell upon taste whether they’re past their prime. Through smell, touch, visual inspection, and taste you can determine whether an avocado has spoiled. (OK, but taste would be my very last resort.)
