So I just watched the video below:
It is said that on the ISS, dirty clothes are considered trash, because they don't wash them. Instead those are packed with other types of trash and will be disposed like trash. I understand that wasting water for washing clothes is not desirable, and the facilities that will be needed to wash clothes in microgravity isn't easy to make either. But in long term mission like going to mars, if we can't recycle even our clothes, then the amount of spare clothes can be needless mass.
So perhaps we can design some form of self-cleaning clothes, or clothes that are extremely easy to clean without the need of water? There is also the possibility of just, well, being naked for the whole mission and skip this whole clothing business, though I wonder if we will get down to it.