I bet there are more stories about screeners and missed flights account of stupidity than we want to read or know about. A friend of mine recently made a trip and the screener threw out all of the liquids in his bag but he left his gimme pocket knife untouched.....
Since many of us that read this board are either old and grey or old, grey and fat (as in my case) we certainly look and act like males of middle eastern descent between the ages of 15 and 45 that could represent a possible threat to airline safety.