I don't think it has anything to do with manners. I think it has to do with boundaries; understanding your own, understanding other people's.

A lot of people are in therapy because we did not get unconditional support or love as children. And when people do get unconditional support for the first time, I think they're thrown off kilter. It's not that they don't have any manners, it's just intoxicating to be able to ask or say WHATEVER YOU WANT, and no one is going to "be mad at you."

It's natural for people want to explore the limits of a new found space. Having the freedom to say whatever ridiculous thing you want and not be told that you are "bad" for it can seem strange.

Once people get used to the idea that the support is not going anywhere, I think it will be easier for them to stop asking their inappropriate questions.

I think it's pretty much either "testing the waters" to see if the support waivers,

or

people with erotic transference attempting to get to "know" their Ts.

Either way, a good T will redirect the conversation back to the client, but be supportive and understanding, not angry/annoyed/frustrated.