Every professor has a view as to what is true and what is not. My English teachers has strong opinions about the literature we should read for the course and about what this literature meant. Frankly, I would wonder about a teacher who had no strong views about these things. After all, they have devoted their working lives to literature. Now, as to evaluating the work of their students, things can get complicated. Many students will produce papers and exams that aren't very good. A humane prof might try to find something good in what is turned in, if only to encourage the student. However, some students will do very good work. A good prof knows what is good and what is not. And where a student has a take on things at odds with the professor's take, a good teacher knows to encourage that student in his or her independent thinking. Soem teachers, however, will do what Chuck condemns and punish a good work because it doesn't agree with the view of the prof. But such is life in school, I guess.
I had a prof in grad school. Neoclassical economist to the core. For a seminar, I wrote a paper on the so-called Cambridge controversies in the theory of capital. I sided with the critics of the neoclassical theory, including the radicals. My teacher told me he couldn;t understand my paper, so he gave it to Dave Houston, the department's notorious radical (one of the founders of URPE), to grade. I never forgot this. A prof who had a view of the economy diametrically opposed to mine had the integrity not to grade what he didn't know about.
I had a student once who gave answers to the final exam in economics in verse. You have to appreciate such a thing, even if some of it wasn't quite correct.