Bodyform, the English version of Libresse, apparently wondered that. They released the first commercial with red blood being dripped on the sanitary pad.
In films we often see enough blood and that is red. What makes menstrual blood in an advertisement different? Menstruating is normal and showing it should be. In the commercial you see, among other things, a man buying a sanitary towel and having menstrual blood running over one leg while taking a shower.
