Explanation: The ancient Romans used the xylospongium or tersorium for wiping purposes - a sea sponge on a stick. How lovely! In public restrooms, they would have been shared, which is probably not all that hygienic regardless of the fact that they rinsed the sponge after each use, or let it soak in vinegar or salt water when idle. Still, civilization! What marvels, right?
Well, the sponge itself would be rinsed of fecal matter in running water, and the salt water/vinegar soak would have taken care of the rest. Smell (at least, the smell of the wiped Romans) wouldn't have been a problem - transmission of parasite eggs from fecal matter, on the other hand? Probably a non-negligible issue.