In The Game of Words, Willard R. Espy writes :
Misplaced commas have resulted in curious misunderstandings. It is said that an ancient Greek, consulting the oracle at Delphi as to whether he should go a-warring, was told:Thou shalt go thou shalt returnnever by war shalt thou perish.Optimistically adding commas after 'go' and 'return', the Greek took up arms, and was promptly slain. He should have put that second comma after 'never'.
Punctuation errors have not caused me such an existential crisis but there have been occasions when my dictation has caused raised eyebrows. For instance, Jaya wrote the title for my first post and looked at me with the quizzical expression that I had when I first saw a report from a management consultancy firm having the legend 'This page is intentionally left blank'. I looked at what she had written - 'Why I do?' I told her that 'I do' is within quotation marks. Now I didn't look so illiterate.