Papers from the Ancient Roman Toilet Workshop, held at the Royal Dutch Institute in Rome and the American Academy in Rome in 2007 reviewed at BMCR by Jane Draycott at the British School at Rome:
A concerted effort is made to address the most common assumptions about Roman toilet usage, such as the extent to which Romans used sponge-sticks, or treated the public latrine as a place for socialising, or placed containers at street corners to collect urine for fulling. Further examined is the later reception of certain aspects of Roman toilets. This includes the survival of references to the emperor Vespasian's tax on urine in the modern Italian name for the urinal, the 'Vespasiani', and the (inadvertent) use of rosso antico Roman toilet seats in papal investitures, which gave rise to the theory that they were used to confirm that the candidate was, in fact, a man.
Full review here. Thanks to MA for the hat tip