I disagree. If all we have are anecdotes then, given the huge amount of travelers and anecdotes at many order of magnitude lower rate, I think that shows the majority are doing things right.

And it's quite possible to tell if something's being done right without knowing SOP. A few weeks ago, my gate at DFW was directly opposite a checkpoint. I watched two standard pat-downs done (they appeared to be WTMD alarms). I don't know the SOP, but it was 100% clear to me that they were done properly. Why? Firstly, because I saw two TSOs do exactly the same thing. And secondly because it made sense: the goal of the pat-down was to search for objects hidden under the clothing and what was done was consistent with that goal.