I don't want to do too many negative posts, but after I found this I had to mention it: one of the worst songs ever written for a movie, and one of the worst scenes from a movie from a great director, is "Wildcat Jones" from Howard Hawks' Red Line 7000 (1965).
The really sad thing about Red Line 7000 is that you can see Hawks trying to do all the things he'd been doing in action/adventure movies for decades (by the '60s, all his movies were largely re-hashes of his earlier work, or Hawks "greatest hits" compilations where people in the know could pick out where each bit came from). But it just doesn't work with the less-than-adequate cast, script, music, set design and photography. Most other Hawks movies had a singing scene, and most of them were good, but for this scene he used a really atrocious song, poorly delivered by his latest attempt to create a new Lauren Bacall, Gail Hire, and with a weirdly-gyrating group of backup dancers (including the young Terri Garr).
The only thing that makes the scene palatable is the occasional shot of Marianna Hill. Who probably should have been up there instead of Gail Hire, since Hill actually could sing and dance.
Not long after this movie was released, Hawks participated in a Q&A discussion with film students and fans, and one question was: "I have trouble convincing my friends that Red Line 7000 is a masterpiece. What should I tell them?" To his credit, Hawks' response was what it always was when he made a bad movie: "I don't think that picture is any good."