Well, most movie special effects folks I know make their monster-goo edible and sweet (in the name of safety).  I'd lay even odds that it tastes like corn syrup.  Or nothing.  The Ghostbusters slime had no taste, it was basically watered down pie filling with food coloring.<br/><br/>Out of character, anyway.<br/><br/>In character, it probably tastes like<strong>Consequences</strong>.