I'm a valid F1 student in the US and thinking about traveling to either Mexico or Canada while I'm here. I've been hearing a lot of stories lately when border officers decline entrance for returning students. For example, my DSO told me yesterday that a married Polish couple (both in F1) was separated at the border after returning from a Mexico vacation (wife was let in, husband was declined entrance). He said their paperwork was fine. Also a few Indian students and an African student were denied entrance this year just to my school (all of them were returning students).
Is there any kind of statistic on how many people were declined entrance when crossing the US/Canada or US/Mexico border by plane or car? I know each entry is up to the individual immigration officer, so how can I be confident to travel?