Put the tamarind paste and 1 cup water in a large pot; stir to combine. Bring to a boil over high heat.
Wrap the cloves and cinnamon sticks in cheesecloth and tie with kitchen twine. Add to the pot, along with 8 cups water, the tejocotes, piloncillo, guavas, oranges, pears, prunes and raisins. Bring to a boil, then reduce the heat and simmer until the fruit has softened, about 30 minutes.
Pour into coffee cups or mugs, adding some fruit to each cup. Add a shot of rum or brandy, if desired. Serve with a spoon.