Okay, actually: things I found while looking for other things.
Some years ago, author Neil Gaiman interviewed Lou Reed. And lived to tell the tale. Verbally en route to the actual interview, Gaiman tells this story:
A friend is in a band that covers Reed’s song “Perfect Day,” but somehow has never heard Reed’s version. Gaiman plays it for him. The friend’s response: “He’s singing flat.”
“He can’t be singing flat. It’s his song.”