Every time I have shipped my bike by air, TSA has opened the box and inspected and collected samples at various places inside the box. They hardly ever lifted anything out of the box, especially if they could easily reach inside.

From TSA blog site:
"ETD tests are used in checkpoint, checked baggage, and cargo environments. We swab things such as laptops, shoes, film, cell phones, bags, wheelchairs, hands, casts - you name it. Certain procedures call for an ETD test.

Basically, our officers run the white swab over the area in question to collect a trace sample. They then place the swab in the ETD machinery which analyzes the sample for extremely small traces of explosives. The test takes a matter of seconds."
The TSA Blog: Explosive Trace Detection Usage Expanded: Give Us A Hand

I've always had good experiences with our local TSA folks, PDX. I just talk to them and am polite. I also pack our bikes so they are easy to inspect. I have never shipped my wife's bike uncoupled. It is more hassle than it is worth. I also only use minimal tape where I want the TSA folks to open the box. They always do a much better job of retaping than I do.

They have even let me take photos of them at work, which is unusual.