I always opt-out too. It's a matter of principle, I refuse to have my privacy invaded like that without being able to see who invades it, plus it creates more work for them.

Also, I rather enjoy pat-downs. They're like a massage, and the TSA agents wasn't too overt with the problematic regions, although they did try psychological manipulation to make me feel bad (refusing to let me touch my stuff, making me take my belt off, etc). I didn't mind, though, opting out felt like a big "fuck you" to the TSA.

Of course, I don't even live in the US, so I've only done it twice.

Not touching your stuff isn't psychological manipulation. It's to prevent you from interfering.

I think that is an unfortunate attitude. I always opt-out. It's a form of civil disobedience and governments don't like that, so they enact procedures that try to discourage people. If enough people opted out, the whole system would come to a stand-still and they would have to rethink the policy. That may mean just removing the option of a pat down altogether, in which case I imagine there will be a large backlash. The real fear for me is that people just become accepting of it slowly over time, until they finally can remove the option and then not enough people will be outraged.

Personally, I will never ever go through one of these scanners. I don't think they are a health risk or anything; it's a matter of principle and they are known to be ineffective anyway. If some poor schmuck wants to pad me down, so be it.

(btw, I am German and have received the most thorough pat down, ever, in Germany)

I think a crucial observation here is: How many terrorist has the TSA stopped? ... Not a single one. All this effort, the lines, the money; and not a single catch.

An effective deterrent catches no one. An A/B test is needed, but...

That's the common argument of those who advocate tighter security.