Scarlet Woman

New Testament  a sinful woman described in Revelation 17, interpreted as a 
figure either of pagan Rome or of the Roman Catholic Church
regarded as typifying vice overlaid with gaudy pageantry

That's the dictionary definition for scarlet woman. While I liked the idea of scarlet woman having risen from "The Scarlet Letter," apparently it has biblical roots. Still, I think it was intentional that the letter is scarlet.