Cooked chicken is only good for up to 2 hours at room temperature. If left out any longer than that, it should be thrown away.
When cooked chicken is left out, a multitude of bacteria begins to grow. Spoiled chicken tends to have a rotten smell but that is not the only determining factor. Even if the chicken appears to be fine, it can lead to many sicknesses or even death. It is best to discard any food that is not refrigerated after two hours. The food may spoil quicker if the room is especially hot. After cooking, always make sure to keep food warming or on ice to prevent any illnesses.