(as) happy as a duck in Arizona
Unhappy or miserable. The predominately dry, desert environment of Arizona is meant to contrast with a duck's aquatic habitat. Her date never showed up, so she's about as happy as a duck in Arizona right now.
happy as a duck in Arizona
Unhappy. Ducks like water. Arizona is a largely arid state. Ergo, an unhappy person would be as unhappy as a teal in Tucson. Contrast that condition with someone who is as happy as a clam at high tide or as a flea in a doghouse.