Why do people in our TV series show bleeding in their mouths when they are dead or stabbed?

Bleeding from injury is a good image, and it is easy to associate bleeding with death, but what about bleeding on the face? Bleeding on the skin is slow. If there is no wound, it will make people feel disobedient. Seven orifices bleeding is relatively operable, but eye bleeding looks a little oozing on the screen; Nosebleeds-nosebleeds are really common images in daily life, and it is difficult for people to intuitively associate them with "dying"; Bleeding in the ear-Emmm and face are not on the same plane, so it is difficult for the audience to see, so bleeding in the mouth becomes the best choice.