Hyphens, En Dashes, Em Dashes

Q. Is it OK to hyphenate a word at the end of a line that is already a hyphenated word? It looks really awkward to me, and I always call attention to this double hyphenation when I am editing/copyediting. Am I being too prissy? I can’t find anything about this in Chicago.

A. CMOS 16 covers this at section 2.109: “When it is a question of an intelligible but nonstandard word break for a line that would otherwise be too loose or too tight, the nonstandard break (such as the hyphenation of an already hyphenated term) may be preferred.” In other words, sometimes the ugliness of a double break is preferable to the ugliness of bad spacing.