The scary thing is that something always does happen that accentuates your initial preposition against this “tremendous” calendar date.
Walking under a ladder or seeing a black cat on a Friday 13th won’t kill you (not that I know of at least). For what happens if your favourite pet cat is black? Or if you are employed in construction and happen to work with ladders? Or worse yet, if both apply to you?
See, it’s a strange date.
Perhaps it is also because you expect something bad to happen, that whatever out-of-the-ordinary does happen on this date is interpreted as such.
Then again if confusion strikes and you can’t get your work done because other people fail to deliver their part of the deal; or if you get lost on the road due to wrong directions given; or better yet if your entire power is cut off – well, then it is arguable whether this is due to a superstitious date, or in fact the all-round stupidity of people who regularly prove that common sense is indeed not as common as it sounds…