Eating bad shrimp will lead to foodborne illnesses, so you must learn to determine when shrimp has gone bad. Bad shrimp has a strong bitter flavor and an intensely sour taste when cooked. In addition to the weird taste, bad shrimp will also have a strong off and rancid smell. On the other hand, you’ll know when a raw shrimp has gone bad when it gives off a strong fishy and ammonia-like scent and taste.