My mother had the most beautiful handwriting I have ever seen, & very fancy. Sometimes I had to look at her capital letters twice to decide what it was.
Between faded ink and microfilming, determining the correct name can be very difficult. Also one may not be able to tell if more than one person's writing is on a document.
Poor indexing was the cause for my ancestors mistaken name, Warman mis read as Harman. If you look at the actual census ,you can see it is a W, not an H .