In commenting on the famous Otaru, Hokkaido, bathhouse case, Gregory Clark cops out when he says that barring drunken sailors and applying tests of drunkenness are not the answer. It's pretty clear when someone is over the limit. You throw out drunks by throwing them out!
Clark mentions the lack of bathhouse etiquette among foreigners as a problem. He says he understands why "regular Japanese customers seeking the quiet Japanese-style camaraderie of the traditional Japanese bathhouse would want to flee an invasion of noisy, bathhouse-ignorant foreigners."
I have lived in Japan long enough to know this. Yes, there are often foreigners of different vibes in a Japanese establishment. But how far does Clark believe that Japanese people's right to discriminate should go? Only bathhouses? What about bars and restaurants? A globalized, fair nation does not discriminate against a race or nationality.