College teachers, junior college instructors, et al.: do you look up your students' grade records?

Do you ever look up the academic history of your students, either as a matter of course or out of curiosity? Or does every student come to you as a tabula rasa?

If you do look them up, what is the reason, and how does it affect your estimation of the student?

I am assuming that professors and instructors have access to students’ academic records. Is this the case?