Being a student in law school is much different than being a practicing attorney. That said, law school is the foundation that your legal career is built on. As your career progresses and you build your reputation, law school fades away, but it never completely disappears.
If you are in law school right now, be mindful that your interactions, work, and relationships have a strong impact on your legal career.
Need a reference?
At some point, you will need a reference for a job. Even if your grades are outstanding, employers want to know what you are like. Naturally, your professors are a common reference. If you generally skip classes or put forth a half-hearted effort in class, good luck getting a good reference from a professor. If you do not think they are paying attention, you are wrong.
Is this common sense? Of course it is. Some law students, however, seem to throw common sense out the window.
Do not burn bridges
I had a couple professors that I was not very fond of, but I doubt they ever knew that. Sure, if you have a legitimate concern and can approach it in a respectful way, go for it. That can be easier said than done. In addition, you have no clue when you might run into that person again.
Maybe your professor is a mediator. Maybe your professor will become a judge or magistrate one day. Maybe they will forget that you threw a temper tantrum over a grade or told them they were the worst teacher ever. Maybe you really are naive. Those things can come back to bite you in a big way.
Your goal should be to create relationships and build bridges, not burn them.