Quote from the New Yorker, from some years ago, that I like so much that I typed it out and saved it:

Perhaps the most dramatic moment in all the Stanley Brothers' hundreds of recordings occurs in the chorus of "Rank Strangers." After Carter sings the verse, Ralph enters with the words "Everybody I met/ Seemed to be a rank stranger" in a voice that stabs like an icepick. He raised the tension in the Stanley Brothers' music to the nearly unbearable: singing above Carter's melody, he would hang on a dissonant note in anticipation of the chord that was about to arrive. Over time, these harmonies became wilder, more edgy and attention-getting - a separate drama that didn't cozy up to the melody but defied it before an ultimate reconciliation.

- David Gates, The New Yorker, Aug. 20-27, 2001