The sluttyness has nothing to do with nudity. The character in the movie meets the guy for a few seconds and then follows him for sex at his apartment.
The Little Mermaid cartoon character doesn’t behave anything like this.
As I said, it’s been a long time since I’ve seen that movie and I believe you, but honestly I don’t remember the sex scenes, probably because it was PG or PG-13 sex. And I guess I think of “sluttyness” more as a gal having sex with lots of guys but YMMV.
And honesty when I hear of a girl named Madison, I tend to think of the 4th POTUS and not the slutty mermaid just as when I hear of a girl named Reagan, I think of the 40th POTUS and not the possessed girl from the Exorcist.
With that being said, parents should give more thought to what they name their kids. I knew a gal named Tulsa, her parents being originally from Oklahoma. They didn’t consider how cruel kids could be, especially those that figured out what Tulsa spelled backwards spells.