In the movie Tommy Boy, when Chris Farley and David Spade are driving down the road and neither one of them admits they want to listen to her singing "Superstar," and in the next scene they're both singing along and crying, that's how a lot of people feel about her. She was so syrupy I never wanted to admit I liked her, but she projected this incredible vulnerability that would suck you in and open you up.
I wish I could explain it better, but when you listen to Karen Carpenter sing, she makes you as vulnerable as she was.