What would happen if men sitting around the campfire repeated for generations the story of a sexually unsatisfied wife of the ruler trying to seduce the handsome young man who worked in her household? It doesn't take much imagination to realize that details would become more salacious and accounts more vivid with the passing of years.
To see this in action, compare the accounts of Joseph in Genesis and Yusuf in the Quran. The original Biblical account, while not quite boring, is pretty straight-forward. A handsome 17-year old boy is sold by his jealous brothers as a slave in Egypt. He catches the eye of his master's wife, who tries to seduce him. He refuses and leaves the house, but makes the mistake of leaving behind an item of clothing. Hell hath no fury like a woman scorned was as true thousands of years ago as it is today. She tells her husband that Joseph tried to rape her and that the shirt is the proof, and the furious husband throws Joseph in jail.
Fast-forward hundreds of years, where a young Meccan boy on a camel caravan hears these ancient stories at nighttime from Jewish and Christian merchants from destinations as far away as Jerusalem, Damascus, and Constantine. He later recounts many of them but they have a different, spicier, flavor. Here's an abridged story of Yusuf in Sura 12 of the Quran, beginning with the first mention of his interaction with his master's wife:
She closed the door and said, "Come on, come on!"
"I can't," he replied, "Wrong people like you will never be successful."
She really wanted him, and he would have responded to her if WE (Allah) had not protected him because he is one of our chosen, guided slaves. So she and Yusuf raced each other to the door and she ripped the shirt from his back. He flung open the door, and there stood the husband!
"Help!" she screamed, "He tried to rape me! What are you going to do to the man who tried to rape your poor wife? At least throw him in prison or torture him."
"No!" Yusuf replied, "She tried to seduce me."
The husband didn't know what to do. But then one of the other household servants came up with a brilliant idea. "Look at the shirt," he said. "If it's torn from the front, she's telling the truth and he's a liar. If it's ripped from the back, she is the liar and he's telling the truth."
They looked at the shirt and, sure enough, it was torn from the back. "Oh, you nasty woman," said the husband. "You are a schemer. Yusuf, stay away from this troublemaker. And you, conniving lady, say you're sorry."
Well, word got around and soon all the women in the city were talking. "She's trying to seduce her young slave," they said. "She's so in love with him, but she's plain wrong."
The wife heard about this and thought of a plan. She prepared a big dinner and invited all the ladies. She gave each of them a sharp knife to cut the food. Then she commanded Yusuf to come into the room and let them see him for themselves. As soon as they saw him they lost control of themselves and in their amazement cut their hands with their knives! "He is so handsome," they said, "He's not a man, he's an angel!"
"So now you understand?" she said. "You see? And you were blaming me because I wanted to sleep with him? But he turned me down. If he refuses me again, I'm going to have him thrown into prison."
But Yusuf turned her down once again and off to prison he went.
A Muslim, of course, would strongly disagree with my suggestion that Muhammad's rendition of the story was anything other than the angel Gabriel directly speaking the words of Allah into his ear. The Quranic account is the perfect, unalterable, word of Allah because....well, just because it is.