It's a shame to know that Elaine Stritch had many nights where she flubbed lines terribly, but I must say that the two times I had the privilege to see her, she didn't flub her lines once. The worst it ever came to was she paused for a slight second at the beginning of act two for the line "We mustn't be seen sitting around like bohemians." Other than that, she was on her game.
I will say that the most blatant "I don't care" performance I've seen recently was Chester Gregory in Sister Act. He just stood around on stage, barely looking at anyone and pretty much just throwing his lines around. The only time he put in any effort was his one song. I'm sad to say that because he put in an effort for that one moment, the audience still gave him a big round of applause.
"Sing the words, Patti!!!!" Stephen Sondheim to Patti LuPone.