What visual characteristic creates a primary source of confusion between a black sable and a solid black GSD?

A heavy black overlay or very dense sable ticking appearing black from a distance.

The primary source of confusion when comparing a black sable and a solid black German Shepherd arises from the visual overlap caused by the intensity of the sable coloration. In a black sable, the banding of color along the hair shaft is so heavily dominated by black tipping, or the sable ticking is so dense, that from a distance, or under poor lighting, the dog appears entirely black. This visual presentation mimics the uniform pigmentation of a true solid black dog, whose hair shafts lack any banding whatsoever. It requires close, often bright-light inspection to discern the subtle variations in color along the individual hairs that confirm the presence of the sable pattern.