I have been "randomly" singled out on every commercial flight so far since 9/11/01, and I'm always prepared for it. However, the first time it happened (at LGA) I was annoyed by the lack of organization and foresight. They had no place for us "suspects" to stand, and the small team of screeners seemed to not be sure which one was to do what. It actually delayed the flight- we all got aboard well after the others.
But in general I've found them courteous and efficient, and I really want one of those mats with the footprints- that'd make a great doormat!
  But despite being subjected to every personal scrutiny short of the procedure involving a rubber glove (wonderful to be assured that I am not a hijacker, let me tell you!), how am I supposed to feel safer when I see that the checked luggage and cargo are going aboard without any inspection?   The promised improvements in that area have yet to be fully realized, mostly due to the usual problem: money.