Don, I agree that most audiences can't tell if you make a mistake if you act like you did it on purpose. But that doesn't mean the mistake lyric is as good as the correct one. Sometimes it just means the audience wasn't paying that much attention to the lyrics or maybe that they'll just be less impressed with the lyrics than they might have been without the error.

"I don't create new arrangements with my mistakes. If I make a mistake I make sure I don't repeat it next time."
Maybe you won't, but other people who heard the mistake might pass it on, without realizing it was a mistake.