Well, I doubt a girl would just say it without meaning it. Girls love to be called beautiful, I don’t know what girl doesn’t. It depends on who the girl is. It’s kind of difficult because it’s a confusion on the girl to not mess anything up on her response. If you call her beautiful, just leave it at that, a boy calling a girl beautiful will remain in her head forever. Girls don’t forget about what a boy does/says to them.