Which specific aesthetic trait did breeders rigorously select against when refining the German Spitz stock?

Answer

Remaining off-colors or slight cream tinges

Breeders focused intensely on standardization, rigorously selecting against any remaining off-colors or undesirable traits carried over from the original German stock to achieve the pristine white specimen.

Which specific aesthetic trait did breeders rigorously select against when refining the German Spitz stock?
Caninedog breedancestorspitzJapanese Spitz