Vampires - Bad BLood

“The general rule is, never drink from a person who has been dead more than a day,” Mr. Crepsley explained.

“How will I know how long a person’s been dead?” I asked.

“The taste of the blood,” he said. “You will learn to tell good blood from bad. Bad blood is like sour milk, only worse.”

“Is drinking bad blood dangerous?” I asked.

“Yes. It will sicken you, maybe turn you crazy or even kill you.”

***

Cirque Du Freak: The Vampire's Assistant, Chapter 4