I know this is an unpopular take on it, but I feel that considering how poorly paid they are and what they have to put up with, most airport screeners are very professional, and pretty sharp.
If they were sharp.. they wouldn't put up with the conditions, or the pay.
I'm not indicting them, as much as the situation of which they're just a symptom.. Not everyone is an aspiring engineer or surgeon. If you offer 8 dollars an hour, to do a 15 dollar an hour job... this is what you end up with..
Good point, but it beats flipping burgers or handling baggage. All I know is: they're not all idiots... which is more than I can say for those who set the whole thing up (who make a lot more than the screeners!)

And again: although I