For my foam applicators, I throw them in the wash with my cotton towels, or my LC pads if I used them. I don't have MF applicators, nor do I use MF to apply products. My MF's are for product removal only, so they don't get saturated with anything. They are washed seperate from everything else.
My applicator pads come out nice and clean, even if washed with my LC pads on the gentle cycle. I pre-soak them in Dawn (in the kitchen sink when the wife's not home), then I use liquid laundry detergent, with maybe a capful of Simple Green, in the machine. And if they look questionable after a wash, I start using them for wheel wells and for tire dressings. I found them at a dollar store for $.99 for a 4 pack. I stocked up!
Dave