There's a new production of West Side Story on Broadway, and the New Yorker review includes the following passage:
Laurents’s most innovative touch is to have the Puerto Ricans sometimes speak and sing in Spanish. Fifty years on, in a multicultural America, this decision makes the production feel fresh; it also allows the show to dispense with some of Sondheim’s rookie mistakes. In “I Feel Pretty,” for instance, he had Maria, an uneducated Puerto Rican teen-ager, only a month in New York, singing with such showy internal rhymes as “It’s alarming how charming I feel.” (“When rhyme goes against character, out it should go,” Sondheim said in 1974, with the wisdom of years.)
The passage has stuck in my head, for what it says about the odd mix of realism and artificiality in a musical. Replacing "rhyme" with "language" in the Sondheim quote would make it far more obvious and less interesting; sure, you shouldn't put words into a character's mouth that she wouldn't use. But certainly, no one would ever break out into spontaneous song (and dance) the way Maria does, so the thought that the rhyme scheme in that song can somehow be too linguistically sophisticated and thus uncharacteristic intrigued me.
(Of course, having the Puerto Ricans sing in Spanish only works, I assume, because just about everyone already knows the songs.)