That sound in tune to you? … Sounds sharp to me. Sounds like I'm playing sharp all the time. My singing teacher told us you should do that. Maybe I got it from her. She said singers when they grow old have a tendency to go flat. So if you sing sharp as a young person, as you get older and go flat, you'll be in tune. In other words, it's never thought good to be flat. It means you can't get to the tone.

Listening to a long solo on Mingus at Montery, as quoted in Mingus/Mingus : Two Memoirs (1989) by Janet Coleman and Al Young, p. 10