If I ever need to feel lucky, I read threads like this. In the last 24 months I have passed through TSA checkpoints approx. 267 times, in 40+ different airports around the US. I don't hold a US passport, almost always just have carry-on bags (and therefore have packed a reasonable amount into them) and I can confirm that:

1. I have never once had any more interaction with a TSA agent other than "stop. go. let me check the size of that liquid container. let me see your boarding pass."

2. Never once have I been asked about my travel plans, where I'm coming from, where I'm going, what sort of mood I'm in, who I'm going to see, etc.

Having said that, I think the whole process is incredibly inefficient compared with travel through airports in virtually any country in the world (I recently spent a while in East Africa and was shocked at how polite and painless the whole airport process was) - there is a lot they could learn in the US. But for those of you who think that you are continually being monitored for the slightest reaction and have to have pre-rehearsed lines to make it through the checkpoint without being "detected" you are reading far too much into things! Don't forget - behaving like that just means they have won