Maybe it's because I am 6' 2", blonde hair blue eyes, with a reg haircut...but I never get bothered going through security. I've probably flown commercial on an average of 4x a year since I was born...many more when I was a minor, not so much now that I am government issue, and I have yet to be pulled aside. Before 9/11/2001 I went through with all sorts of crap, pocket knives (think Boy Scout knife, not Bowie) and weird electronic toys...I even threw a vibrator in my friends bag in college to fuck with her, nothing!
After the security tightened up I was pretty good about sterilizing my gear before going in, but still, I figured at least once...
I do have to say that after about 2004 it seems everyone got a clue and 90% of people that are regular travellers seem to be ready at the checkpoint...none of that deer in the headlights "you need my ID?" shit anymore...and the other 10% are getting better at figuring it out. I went through LAX and OKC back in February and both lines were pretty fast...especially considering I hit the morning rush in LA...
I like the appearance of security that TSA gives, between what they actually catch and keeping Mr. and Mrs. Joe America happy to fly feeling "safe" they do their job (a little placebo effect)
I have no idea on what goes on behind the scenes there, I'm sure that TSA is far from the last line of defense against the swarthy horde of shoe-bombers, but they are good at preventing the average idiot from walking through with a gun and a bad attitude. They have a shitty job, noone really appreciates what they do, it's a little like being a traffic cop or a prison guard...nobody wants to be them, but we still need them to keep society happy and running.
I still prefer to be polite and treat them like a human being when I deal with them, and have yet to see them do any less in return...