The viscosity of zombie blood has always intrigued me, as displayed in this comic. It is apparently quite thick, though doesn't always cling to clothing. At other times, it turns your clothing green, making it time to get a new wardrobe. That is, unless your clothing was already green.
Sidenote: always check trashcans for toxic refuse and/or the undead. They tend to pop up when you least expect it, necessitating drastic measures.