Ah, the smell of coffee in the morning, smells like... victory!
A theory, for you to disregard completely: the best tasting foods are on the very edge of rotting. Our taste buds naturally evolved to detect bad food, so they are hyper sensitive to spoilage, and foods which are somewhat spoiled and yet not trigger the strongest taste sensations. Consider cheese for example, or wine. So it doesn't surprise me at all that the wonderfully-named putrescine is a key ingredient of coffee.