If you look at business travel a good portion of visas are approved.
If you look at single female the refusal rate is extremely high because of the trafficking issues in prostitution and massage.
Sure if you pull all applicants together I could see the percentage of refusal being in the 20+ percentile.
I would bet a years salary that they might approve 1 out of every 200 single females and that this category is the highest rejection category with single males under 35 the next.
The US does not want women in prostitution nor do they want male overstays working unauthorized.
I have a friend that works in one of the Asian embassies (not Thailand) and he has pretty much explained how applications get processed. And there are so many variables one of which is visa return status for prior holders. When they have more overstays for a period they reduce approvals. There is an unofficial cap which contributes to future approvals.
And let me add that this is one of those situations that knowing someone inside really does nothing because in many cases the approval is not done at the local level.
And I was being sarcastic with the questions in my post.
You better make sure she knows your birthdate, how old you are, what town and state you come from, where you worked, the names of all your family members, the names and ages and birthdays of any children from a prior marriage, your blood type, your medical history, the names of your parents, the license plate of your car as well as the make and model you drive in the states, etc.
I am being dramatic but when you get to the interview stage they are going to deny her if she doesn't know a good portion of that.
It's easier to get her a plane ticket and visa to Mexico and have her meet you at the border in Texas. When you guys are done visiting she can fly home. 😉