I came across this one yesterday when I was looking for more information about something mentioned on HN:

    Search:  carmack +zfail gpl
      Date:  2011-11-02
    Result:  Bad autocorrect; Plus operator broke
    """
    Showing results for carmack fail gpl
    Search instead for carmack zfail gpl
    """

Because the plus operator is broken my final search ended up being `carmack "z-fail" OR "zfail" gpl` because different sources included or excluded the dash. Note that I think it's good that quotes are still exact and they shouldn't do the synonym search, but this is something the plus operator would have worked on, if I remember correctly.