Leprosy came in many forms, just like sin. Priests could identify it under the skin, in a scab or as an open wound. Whether it was white, red or dark; a boil or inflammation... whether it was on a man, a woman or in a piece of cloth; on the head, in a beard or wherever else... it was a serious problem. Being a leper would get a person banished from society (Leviticus 13:45-46). The implication by comparison is powerful. Morally, we stand naked and shameful... we are unclean in the eyes of God. We are defiled and are doomed to nothing better than to be rejected and alone. Just find the most repulsive physical human image that you can imagine, and realize that in God's eyes, we all look worse than that spiritually.