shopping613: A person does not learn better with a white shirt or colored shirt. However, if everyone else conforms to the written policy (or unwritten policy), the non-conformist generally will feel uncomfortable and it may effect (affect?) his learning. One of my son’s wears white shirts exclusively (even bein hazmanim); others will wear white in yeshiva and colored shirts at other times.
It would not bother me if someone showed up to date any of my daughters in a colored shirt (well maybe it would if it’s pink).