Another potential fear is that the student/parent can’t make the payments but don’t tell you out of embarrassment. Now the loan starts to go into default, your credit gets ruined and the collection calls start. Not sure how everything works but you could find you wages being garnished for repayment.
My parent’s rule was and now mine is that they would never co-sign a loan even for their children. My parent would do anything for their kids but that. Once you do, someone else now can determine your credit rating.