Japan is widely considered to have the cleanest toilets in the world.
Cleanliness is a cultural priority in Japan, and this extends to public restrooms. You'll often find features beyond basic hygiene, such as heated seats, bidets, and even sound-masking devices. The emphasis on hygiene, advanced technology, and regular maintenance contribute to Japan's reputation for exceptionally clean toilets.
While it's difficult to quantify "cleanest" definitively across all countries and contexts, anecdotal evidence and general perceptions consistently place Japan at the top of the list. Other countries may have pockets of very clean public restrooms, but Japan's standards are generally much higher and more widespread.