I would be curious to find out if TSA has ever provided guidance on what questions in general are "appropriate" and "inappropriate" to ask passengers at checkpoints.

I've read about a number of TSOs who apparently feel that asking people about medical conditions is acceptable. And then there are some who feel that asking about medications, cell phone contacts, and other personal belongings are OK. (All of which are beyond the scope of a simple administrative check for weapons and explosives.)

Is there anything that is strictly "out of bounds"? For instance, if a TSO sees something they don't like on my drivers license (like maybe an address, if they don't like people from a certain part of town) can they ask/say anything? And what about if something doesn't quite "mesh" in their mind-- like, say, someone from the "poorer" sections of town flying on a first class ticket? Are they permitted to ask questions or refer them to secondary screening just because of their own possible prejudices or misconceptions?

I'm wondering just how much latitude most TSOs are given, and am really really hoping that they're kept on a short leash (though evidence doesn't seem to support that position).