Maybe I’m just a savage, but I really don’t understand those paper toilet seat covers in public bathrooms. As far as I know, there is nothing you can catch from a toilet seat (assuming normal use; if you are licking the seat, or rubbing various orifices on it, I think you have a different set of concerns). Maybe crabs (do they only hang out on fabricy stuff?). I think anything voracious enough to cling to a plastic ring for hours, then crawl along your skin until if finds an opening won’t be deterred by a flimsy sheet of tissue paper. I think you’d be more likely to catch something from the door handle.