Why is that a problem? I don't mean that in a flippant way. I'm serious. It's a Shower Curtain Liner. It gets wet.
I tend to clean the shower curtain liner between each guest. It amazes me how many times I pull that thing back and see a giant wad of shampoo, conditioner, or soap clinging to the liner. I don't give it a cursory glance while cleaning the bathtub/shower between guests any more. I'd rather not take the chance of a guest standing there in the shower, and seeing something I didn't see hidden in the folds of the liner. I take it down and throw it in the washer. And because it is designed to get wet, I don't worry about drying it. I pull it out of the washer, and hang it up. I don't have to worry whether it is clean "enough". I know it's clean.