Kitchen tip:
If you're making a recipe that includes eggs, crack each egg, egg by egg, into a small bowl or cup just before you add it to the main mixture.
That way, if any one of the eggs is bad, you'll see it before it goes in and you don't run the risk of spoiling the whole batch.
@DavidSalo
I would say also to crack each individual egg into a teacup, so you don't lose all the eggs you already cracked by putting a bad one into them. (Lol, I make recipes with a lot of eggs)
Eggs can go bad in a number of ways. Some will have spots of bright red blood in them. Some will have gone greenish, some will have black yolks. Sometimes they'll have a strong odor.
A good egg should have a bright yellow yolk, a mostly clear 'white' (the liquid portion around the yolk), and no spots or discoloration.
@DavidSalo @Netherbury
I don't worry about the blood spots (fertilized egg, I think), but you want to see that there is an area of the white that is a gel, not digested by bacteria into a watery texture. And a really bad egg smells like sulfur.
@AlphaCentauri @DavidSalo @Netherbury Yeah, fertilized, eat it anyway.
Another possibility is...a chick. If you got them from a farm that had problems. Anyway if you're super curious, hold the eggs up in front of a light in a dim/dark room. Do it anyway, it's cool.
https://duckduckgo.com/?t=ffab&q=candling+eggs&atb=v315-1&iax=images&ia=images
/nosanitize
@AlphaCentauri @DavidSalo I have never seen a bad egg. What do they look like?