Phoebe's dress-up clothes were just plain dirty and a little smelly. She wears them constantly and there are many that are made of fabrics that I'm not sure will wash in the machine well. So, we set up her own dress-up clothes laundry mat in the backyard.
She scrubbed them with a washboard and 7th Generation dish washing soap.
Rinsed them in a bucket of clean water.
And hung them up to dry. Now they smell fresh and clean!
Even if you don't have a washboard and clothes line, I would highly recommend this activity. You could just wash them in the sink or bathtub and either lay them out or put in the dryer. Phoebe really felt proud (plus it took up a lot of time and allowed me to do some things around the house too!)