I have some thoughts. To my way of thinking, extraordinary candidates (and that could mean extraordinarily good or bad) necessitate a little extra research. I never assign a candidate the highest or lowest overall rating without speaking to another objective and independent adult first. As an example, during the last cycle, I had a candidate who I thought deserved the highest possible rating. I placed a call to the school's athletic director and to the head of the college counseling office to gain additional perspective on the candidate. In that case, the candidate had made some pretty lofty claims about how his individual leadership had affected one of the school's athletic programs. I thought it worth checking with the AD to see if he shared that perspective, and in fact he did. In recent experience, I have not felt inclined to give a candidate the lowest overall rating, but if I did, I would also talk to others.
I am not sure that this is the same as asking a candidate for references, which I do not do. Nor am I sure that this is what is going on in your daughter's case. I'm simply sharing my own practice.
As to the question of how the BGO might have gotten the names and contact information of teachers, that's usually fairly easy to find on the school's website. I try to visit most of the schools to which I am assigned on a periodic basis and meet the head of the guidance office. In my example above, it was the guidance office who put me in touch with the AD.