A friend of mine granted that there seems to be a good man presently as the Prophet (we call him President) of the Church of Jesus Christ of Latter-day Saints. Her concern was that a person who wasn't as good might be voted prophet in the future. I don't worry because I know that the Lord chooses His Prophets. God always has. Each man has been prepared and tested all his life for his future calling as God's Prophet. Think of the soul wrenching test Abraham was given of offering his son as a sacrifice before he proved his worthiness. Think of the life of Moses, born an Israelite, but raised in the palace of the Pharaoh where he was taught court etiquette, given military experience, and Egyptian education. He was aptly prepared for his special mission to deal with the Egyptian rulers, lead the Israelite people to freedom, and govern them. This article describes how one modern day Prophet was prepared for his future responsibilities.
I like how this quote from that article clearly explains how a Prophet is chosen.