A while ago, I was eating a bowl of SpaghettiOs, when I noticed a small amount of the sauce that had been on the table a minute before. Not one to waste delicious food, I scooped it up with my finger and tasted it. Much to my chagrin, it tasted of blood. Now, the table's surface had been clean beforehand, and I quickly checked to see if I had been tasting a cut on my finger or a mouth injury. I tasted it again, and, yes, blood. So I preformed an experiment. I took a small amount of SpaghettiOs sauce, put it in a bowl, and let it turn cold. When I tasted it, it tasted like blood. SO, SpaghettiOs sauce, when chilled and in small quantities, tastes like blood.
This has led me to conclude that the secret ingredient in SpaghettiOs is people.