Here is an article from today's NYT addressing the issue:
http://jetlagged.blogs.nytimes.com/2...afer/#comments

The comments are particularly interesting.

I honestly don't know why it would require luck or be a problem to compile a list of methods used for spotting and behavioral detection. It's not like it's a secret art. Sure, the TSA would like to keep their methods under wraps if possible, but after all it's just about psychology and behavior, so some common sense should be able to figure out most of the techniques.

One of the commentators of the article said that he gets very nervous and fidgety in crowded situations. Just like the kind we experience when standing in line at customs or the security checkpoint. So then that person would experience a rise in blood pressure, different breathing, searching around nervously in pockets for where in the hell he put his passport and so forth. And, bang, you are spotted.

Other things might include how you are dressed, like wearing a thick and closed coat inside. Well it might be you are just always cold due to a thyroid problem for example. Oops, secondary screening.

Unfortunately, I am not well versed in psychology and BD so that's why I though it would be good to rely on the experience of members here to see which other techniques they have experienced or know about.

So?