According to ABC News
every year since the September 11 terror attacks, federal agencies have conducted random, covert "red team tests", where undercover agents try to see just how much they can get past security checks at major U.S. airports.
Apparently these undercover agents get away with plenty, but thanks to the transparency of the Obama administration the U.S. Department of Homeland Security have kept those results under lock and key.

Undercover TSA agents testing security at a Newark airport terminal on one day in 2006 found that TSA screeners failed to detect concealed bombs and guns 20 out of 22 times, the news network claimed.

And a 2007 government audit revealed that undercover agents were successful slipping simulated explosives and bomb parts through Los Angeles's LAX airport in 50 out of 70 attempts. At Chicago's O'Hare airport, agents made 75 attempts and succeeded in getting through undetected 45 times.
Does that make you feel good? Whenever the TSA has been tested, approximately 90% of the time weapons have gotten through security screening.  
It seems to me that rather than training TSA agents to look at people naked, and "to touch people's junk," the TSA should be spending more time training its agents to recognize weapons in the screening x-ray.