The "Running Man" isn't really a nebula by itself. Rather, the Man's outlines are formed by the dark spaces within a group of bright nebulae, positioned within a degree of M42. I'm guessing that the dark spaces are due to space dust with very low reflectivity. Anyway, I've seen the The Man in his entirety only once, through our club's 30-inch reflector, on a moonless night of good seeing. The drawing below is the view through my 18-inch Obsession, on a night of average seeing (for northern New Mexico).
More information is contained in Stephen O'Meara's Hidden Treasures, p. 157, and The Night Sky Observers' Guide, vol. 1, p.266.
Roy in New Mexico