My sister works fir the TSA and we talk about this all the time. Its a joke and they all know it. There is no standard training done from airport to airport, no real reason behind why "rule and regulations" concerning things such as the 3oz bottles are done, employees are unhappy (and therefore dont do their jobs right), attrition rate is outragiously high.
My sister, who has worked for the TSA since it was put in place says all it does is look good to the public. The general masses feel like they get searched so they feel secure. Anyone who spends more than a day in the airports observing the TSA could easily pick out the holes and TSA knows it but they wont say anything because its their jobs on the line. They stop the fly-by-night wannabes and joe-blow who is dumb enought to pack a bottle of water but thats it.