A few blocks from New Orleans' Superdome, just off Canal Street, there's a barber shop called Clear-Vue, which has been in business since 1948. While we were in the city for the Essence Music Festival, we asked Jazmine Sullivan to meet us there.When she walked in, patrons and barbers alike were wary. But they knew who she was, from hit songs like "Bust Your Windows" and "Holding You Down (Goin' in Circles)." And when she began to sing, wearing her powerhouse instrument lightly, everyone ceded her a floor that had been previously occupied by a heated debate about college football. To a roomful of captivated men, she sang a brand new song, "Stupid Girls," that warns women to be careful with their hearts.