Quoted Walter Wellesley “Red” Smith by Walter Winchell (Naugatuck Daily News)

Red Smith was asked if turning out a daily column wasn't quite a chore. ... "Why no," dead-panned Red. "You simply sit down at the typewriter, open your veins, and bleed."
---Walter Winchell, April 6, 1949 in the Naugatuck Daily News, p4, column 5

If opening up your veins at the typewriter and bleeding means something with respect to writing, then it must surely mean all the more when typing with a red ribbon on a Remington 666 typewriter which gives the type slugs the appearance of being covered in blood.