From my experience. You can usually tell when the truth has ommisions. It is just a way people tend to phrase things. Most people tend to embelish their answers a little bit. They say a little more than what was asked. Very rarely do you come across a person, who hasn't been prepped, when asked a question requiring more than a yes or no answer, who provides an answer that is stagnet. In other words, rarely will you get answers that provide minimal information. And in those cases you ask for more information. By asking for more information, the ommision becomes harder to keep out. It all becomes a matter training.

And yes I agree there are more "targets" than airports. Will this keep us absolutely safe, no. Nothing will. We need to learn to accept some risk in living our day to day lives.

In the end, I am not sure which of the systems works best, or I am willing to accept. Randomness works only to a limited extent. It removes the predictablity from the system. Interviews work to a better extent, but are time and labor extensive. I think a workable solution would possibly involve interviews for SSSS candidates, and a random group of the regulars. The SSSS (or what ever it is in the future) would still get the secondary while those in the random group who don't raise alarms would be able to go through. After a period of time we should see how the process worked. i.e. did the random group that is redirected to secondary contain anymore on a % basis of bad things than any other population. Just a thought.