Which exam scores are we talking about? Grades themselves are generally by preponderance the result of exams.
In non-thresholded samples there is still a small negative correlation, or no correlation at all. If you could show me a study thay shows big, positive correlations between intelligence and consciensciousness without thresholding I'd be interested.
> And consciensciousness is actually negatively correlated with IQ.
In the same way that SAT math scores are negatively correlated with SAT verbal scores, which is to say only in thresholded samples.
https://sci-hub.se/10.1016/j.paid.2014.06.014