nope...no specific reference....just general stain build-up from not being cleaned well up under the rim. You don't see it if you don't lift the seat...unless you bend way down. This lady's brush did fine on what she could see, I guess............

however, I HAVE seen grossness I hate to mention in public potties. Sometimes I think certain folks wait till they're away from home to make a big mess just so they don't have to deal with the results.

(You know, there are certain functions and habits we are not trained in much and that just are not mentioned much after we are 7-8 years old, and I am of the opinion that in 30-40 years, some very strange variations on private activities can develop.....)