[innocentoldguy]

I agree that diet is a factor. I started living in Japan back in the late 80s and spent a lot of time helping newcomers learn how to speak Japanese and get around in society. One thing I noticed is that people fresh from America had an odd buttery smell that went away after they ate a Japanese diet for a few weeks.

[duffyjp]

バッタ臭い / Battakusai / Stinks of butter was a derogatory term for foreigners in the past. Butter was unpopular with locals in Japan for a long time by what I've read, but I never thought the expression was being literal. Interesting.