The difference here is that Bad_Guy is visiting the country for the first time. Now, there are fewer questions to ask.

But that's a common enough situation that the questioners are going to be ready for it. And I bet a lot of the point of their questioning is just to see if they detect signs of stress where they expect to. If you are a smart person who does something like this 20 times a day, you'll soon get a really good feel for when something odd is going on. Also, any kind of in-depth questioning is likely to uncover a lot of fraudulent claims. If I say I'm a chemical engineer, it's not going to take much depth of knowledge for the questioner to find out I don't know things any chemical engineer would know, for example. (It wouldn't be hard to come up with some computerized system for pulling up lists of questions like this. Like, someone says he's Catholic, and you ask him who was born without sin as a direct result of the immaculate conception, or ask him to say a Hail Mary.) So this might force you to tell more of the truth, which makes it easier to profile you. And this is all physical / procedural security. You're not building an unclimbable wall, you're building lots of challenging speedbumps. No doubt a real intelligence agent would be good at getting through this kind of screening, but that doesn't mean most of the people who want to blow up planes would be any good at it!

Sarad.

--John