I don't doubt that an Andalusian can be good spinners. I've heard several reputable fanciers claim this to be the case. My question is, "Why?"

Classic Andalusian is said to be a combination of HETEROZYGOUS Indigo x homozygous or heterozygous spread black (i.e., blue series pigeons having spread).

Can anyone with enough experience claim that those oddball-looking birds that are HOMOZYGOUS Indigo x spread black, having light-colored body feathering with dark-colored heads, are likewise more likely to be good spinners? (Those that look this odd may be culled before their rolling ability is evident.) How about heterozygous or homozygous Indigo in the ash-red series? Are these also prone to being superior spinners?

Is there any difference in the "hard" or "soft" feathering of Andalusian vs. other "normal" colors in rollers?

Many roller fanciers have found in certain roller strains that certain colors/factors/modifiers produce a higher percentage of quality spinners than the birds of the same strain which are lacking these genes.  Examples include: