The TSO who "assisted" me (there is something wrong about "male assist" as the person who gropes you to prove you're not a terrorist) made sure he touched every part of my body, INCLUDING the bottom of my feet. This foot fetish is a new process to me -- for crying out loud, will we now need to remove socks?
I was wondering about this recently - does the NoS see the bottoms of our feet? I don't remember what the floor of the MMW looks like but I do recall some kind of mat or carpet between the BXSK boxes.
The notion that the "better" scanning method is less likely to catch something than other methods is simply par of the course, of course. But knowing TSA's usual excuses*, they'd probably say they'd automatically catch someone with something stuck to the bottom of their feet because they'd walk in some unusual way. (Read: people with MS, MD, CP, etc. are going to get groped more)
* in a discussion about AIT, a TSA spokesman said they're not worried about body cavity explosives because such a thing would naturally be accompanied by an external indicator like wires or a handheld detonator.