ergophobe - 2:56 pm on May 17, 2013 (gmt 0)
Yes, it depends on your source. Some fonts, for example, have very thin spots (like at the top of the "n"). I've had source materials with some fonts on glossy paper with relatively low contrast that scans as an endless series of iniiiiijjjjinnn
But in other cases, I've seen error rates of less than one letter per page.