When it comes to coloration, it is not an issue unless you are doing some crossing of different strains and trying to breed back to one of the strain looks so you can say it is that strain. Many birds out there having a look typical of a given strain are in fact a product of outbreeding which is often needed to prevent inbreeding depression. The selection for color is a method for "hiding" the outbreeding when potential market is overly concerned about purity.