5. It's an unnecessary expectation to put on others. In the absence of a "bless you," an alternative could be for the sneezer to say "excuse me," as one might with any other involuntary bodily function (ok, gas). That might take the onus off the sneeze witness and allow us all to carry on without worrying we're committing a serious social faux pas. It makes more sense than "you're so good looking," and probably won't end with a door slamming in your face like the one that closed on Jerry Seinfeld's.