TSA has the perfect setup for running an airport theft operation with something close to absolute impunity, and at some airports they've got this figured out. For example, I'm pretty sure they've got a theft ring running here at El Paso International, several years ago they stole exactly $500 cash out of my wallet going through X-ray while a wand scanner distracted me. There's more recent evidence that I can't post about. ....Several days ago, there was a news story that at LAX, TSA was expediting dope shipments. I read the story and wondered "does this really surprise anyone?"
Any time you are in an airport, never let anything out of your sight that you can't afford to lose, even going through screening. Carry your wallet and passport in your hand. If you've got anything you can't carry in your hand (i.e. has to go in the bins through X-ray) and if you can't watch what they're doing with your stuff meanwhile, IMMEDIATELY without leaving the area go through your stuff to make sure everything of value is still there.
If you're carrying substantial amounts of cash or other small valuables that you can't literally hold in your hand the whole time, before anything enters the screening, tell the TSA operative that everything has been counted, and after screening they will watch the recount. (On one trip I told the TSA agent, "serial numbers of all bills have been recorded" which they had been.) Don't for a minute let them think that you trust them, remind them that you are looking for criminals harder than they are.
Usually airlines are working against your interests, but this is a situation where the airlines are your friend. They want security, but they don't want people to be afraid to travel because of TSA harrassment and theft. If you've been victimized by TSA, TSA will stonewall you. Go to the airline to register your complaint if you're going to do so at all. Also remember that if you report a TSA crime, you might never catch a flight on time out of that airport again. They're counting on you being smart enough to figure this out. Reporting TSA crime involves some risk. The best approach is to do your best to make sure that the crime doesn't happen.
You also gotta realize that TSA agents are mostly bored stiff and are pretty much clueless about real terrorist dangers, so they'll relieve their boredom by finding excuses to harrass someone. So, in protecting yourself you want to be sufficiently polite as not to create a situation that will escalate. The vast majority of TSA people are honest and conscientious people trying to do their jobs as best they can, and the problem is that you don't know which ones are the crooks and which ones aren't. So don't let your need for rational paranoia come across as a personal insult.
Then there's that other angle. I recently had to fly, and I'm partially paralyzed. The crutches stayed at home. Why? Because some screwball might get the idea that there's 5 pounds of plutonium hidden in those crutches and I don't have time for that nonsense. If I have to sit on the floor or crawl, so be it. My boss thought I was overdoing it until several days later I sent him a news story where TSA ran a little kid with cerebral palsy through the security wringer because of the wheelchair and leg braces, causing her to miss her flight.
TSA agents are often suspicious of anything electronic that they don't recognize as ordinary consumer electronics. A rep I know recently lost a bunch of stuff because TSA wouldn't let it on carryon, and it was stolen from checked luggage. (Gee, someone knew what was in that luggage?) If you're hauling stuff hoping to carry it on and they make you check it, demand that they secure it with a special TSA security lock. At the destination, you can open it but supposedly it can't be opened by anyone else in between.
Finally, you need to understand that security procedures are unpredictable. Today someone will tell you that thus-and-such can be in carryon and tomorrow you may not be able to carry it on. A lot of this is just plain bureaucratic whim, but some of it is by design because if security procedures are predictable, that's what tells the bad guys how to get past security. As much as we may not like what TSA has done to air travel for the average citizen, evidently the bad guys like it worse. They haven't been blowing up very many airplanes of late.
--Dave J.