Interesting poll, thanks. As I understand it, we don't read words letter by letter, rather we recognise them by their shapes. I remember reading somewhere that our eyes actually scan along the tops of lines, and serifs are intended to aid this process. This reminds me of jumbled up words. For example, "Aoccdrnig to rscheearch at Cmabrigde Uinervtisy, it deosn't mttaer in waht oredr the ltteers in a wrod are, the olny iprmoetnt tihng is taht the frist and lsat ltteer be at the rghit pclae. The rset can be a toatl mses and you can sitll raed it wouthit a porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe." [
Source] So, perhaps scrambled words and misspelled words are easier to read in a serif font.