Depends on if you have any scratches on the interior plastic of the cooler. If it were me, i'd probably clean the grossness out of it then do a 20:1 water to bleach scrub and let it dry in the sunlight. Then, rinse it out and sanitize as usual for your next batch.
Beer so good, it's frightening.
2014: Seven Heavens Series One: Vilon, Mystic Melomel, Skeeter Pee.