Angels do wear red!

When I was a child, in school, we were occasionally given copies of drawings to color in. Close to Christmas we were all handed drawings of angels and told to color them in. I sat happily coloring with my crayons, and made her dress red. Everyone handed their angels back to teacher. She hung them all up on the wall in a row. Except mine.
She looked at me crossly and said mine was not being hung up, because "Angels don't wear red!"Hmm, I wonder if Botticelli's teacher ever told him about angels not wearing red?