Birds from Mary Ann will most like all be good type. You might have a cull or two but don't expect many. Now color is a different thing entirely. Say you get 25 chicks. I'd guess that around 7-10 will be better than all the rest. Those are the keepers.
However, let's say you have a pullet that is a cull but her tail color is near perfect (very, very, very hard to come by). She becomes a breeder to a cock that shows what she lacks. So, don't cull to early with this breed. One of those culls might have one thing you need.
What to do with the extras (besides the Christmas pen)? That's up to you. Neither Mary Ann nor myself run a Hospice for chickens. When you hear either one of us say cull, we mean ONLY one thing. Lots of folks may disagree, but since they ain't sending me money for my feed bill ($75 a week); I don't listen. Don't mean to hurt anyone's feelings. That's just how we do things.
It's also the reason the Mary Ann's Nankins are the Best; I raise them, but not in the numbers she does. I concentrate on Orientals; of which, mine are near the top for one reason; I cull.