MacInTouch: timely news and tips about the Apple Macintosh
...So you would think it was a file in my home directory. Wrong! The culprit was Apple's system level font cache, which caches fonts by user. Deleting /Library/Caches/com.apple.ATS/(uid)/, where (uid) is my user id (just check with get info if you don't know your id - yours is the one you own) solved the problem.