Boyd K. Packer says a prophet need not be a classic example of physical perfection or education; Joseph and other prophets are subject to "frustration and even to failure."
Boyd K. Packer, The Things of the Soul (Salt Lake City: Bookcraft, 1996), 36
A PROPHET NEED NOT BE . . .
Now, there are some things a prophet does not of necessity have to be, and it's perhaps surprising to discover some of these. He need not be a classic example of physical perfection, nor need he be the most intelligent individual who has ever been born. It is not necessary, in order to be a prophet, to be the best educated among all the people of the world; and it isn't necessary, in the final part, to have a personality molded in any special iron-clad mold. Joseph Smith, as prophets were and as prophets are, was subject to disappointment, even to despair; to illness, to fatigue, to frustration, and even to failure. He was just a man, after all, and he had no special immunity from any of the realities of life that prevail for all the other beings who have ever been born.