While it has been quite awhile since I worked at one of those schools, from my time there, we would have said exactly the above. A 65% in math from would not be a red flag from a low performing or even middling public school. It would be absolutely fine. It would be a bigger concern (enough to warrant a conversation in the office but still not enough to completely eliminate a student) if they were coming out a high performing school. So then even more attention would be paid to the math teacher’s recommendation to try to get some context.
Also, referring back to an recent conversation on this topic:
I just wanted to point out that we did mean it when we said that the school superscored. Yes, the admissions offie could see when a student’s first sitting of the SSAT resulted in a low section score, but if that section score went up in a second sitting, they used that section score in their final decision making process. Yeah, we might wonder why the section was low in the first sitting, but it was seen as a positive when a applicant was able to study hard in order to make a significant improvement in the second sitting assuming the other sections didn’t drop dramatically --some fluctuation was expected and didn’t cause concern. I don’t remember a single conversation in which the school worried that the higher second sitting was due to cramming and then forgetting.