One last example, from St. Louis, Missouri. The census taker listed a son with the name "Iman".   Further research determined that the name was actually "Hyman".

The census taker wrote what he heard. For documents, such as the U.S. census, where information was given orally, we must interpret what we see, trying to put ourselves into the mind of the individual who wrote it down — not the mind of the informant. You need to see these types of documents through the ears of the person who wrote it.