I previously had a rental house in Florida. Most folks towel stains came out with bleach but others, which are AVOIDABLE by the guest, such as beach tar , makeup/ mascara, dried blood ( towels and sheets !) red wine on the table cloths, nail polish remover, and fecal stains I had no success. I did take it out of their deposit for the cost of replacement. Many are aware of what they have done and dont argue. Dont forget, if they write a bad review you can always respond online: For example: Thank you for your review. I am sorry you are unhappy for being charged for linen replacement. In most cases normal stains can be removed, however in your situation the BLOOD AND FECAL stains were left too long and had to be replaced for the safety of future guests. Thanks for your understanding.
You can also keep a big bottle of stain remover at the rental with a sign reading:" For stains on linens, please treat immediately to avoid permanent damage and replacement costs. Thank you . " So they are forewarned.
Now that I am living in Europe, i find the majority of guests expect to bring their own towels and sheets! Perhaps you can say you will rent the sheets and towels to the guest like they do here, however the fees are usually just for the care of the linens . Say, if the linens are left in the same condition , you'll be happy to refund 30-50% of the linen rental fee.
In a sense, it can be seen like a damage deposit for linens and not the other items like furniture and dishes.