Scrutinizing students’ research papers would really depend on their teachers, since it is their prerogative to read the papers or just totally scan it. You will never really know, unless you get corresponding results.
If you are the type of student who does not care about the results of your paper, you are most likely to have a low grade. There is no harm done when that happens since your grade just reflects what you did. However, if you get a high remark, it is either you fluked it right, or your teacher never reviewed your work.
If you are the intelligent and persistent type of student, you would most likely to expect high grades. You are the first one to complain about low marks.
Scrutinizing research papers is a tedious task since the teacher has to check for the reliability of the information, style and form, and importantly, the tendencies of plagiarism. Imagine the teacher checking each of student’s papers. It is not impossible for teachers to overlook some errors in the paper, and to sacrifice a bit the accuracy of the students’ grade.
Some teachers are not transparent in giving grades, especially in major requirements such as research papers, because teachers would mostly require students to submit these papers at the end of the term; hence, the student would not have a chance to see the results. The student would not know whether the teacher scrutinized the work or not. This is a sad fact.