In "The Blues Brothers" she sang this when Matt Guitar Murphy (I guess that was her husband's name?) was going to run off with the band and leave her. It was protesting him leaving, but in Respect she sang it when she wanted to get freedom from her husband, so I think in one of those two incidents (probably Respect) the song was used incorrectly?
shareA good popular song has some kind of universal appeal, it's not just good music, but has something in the lyrics that applies to everyone. The best songs can be heard by millions or billions of people, and each one of those people can think of something going on in their lives that makes them want to say "Yeah, think (think) think about what you're trying to do to me" to someone they know... and that's why it sells millions of copies.
That, and it makes you wanna dance.