There's nothing worse than breaking rotten eggs into food, ruining the recipe beyond repair.
Telling the difference between good eggs and bad eggs is actually quite easy. All you need is water and a bowl.
If you dump an egg in a bowl of water and it sinks, then it is fresh. If the egg stands upright, but one end is touching the bowl, then it is not fresh, but it is safe to eat. If the egg floats in a bowl of water, then it is bad.