Having gotten paid for fixing many a fridge and reclaiming a ton in college, the answer was, toss on a respirator, then pour a bottle of bleach in to the fridge (dorm size) and let it sit for a week in the heat. Then open it and hose it out. It was fine. Full size fridge is like 3 bottles of bleach. Also you have to put it on it's back (coils).

Soooo many students were like "This fridge is a loss" and would just give them to me.