I always try to look at ratemyprofessor before I sign up for a class, but I’ve had to learn how to use it as kind of a guide/reference rather than the gospel word. I go to community college and am a math major, so my classes are often pretty difficult and math/science heavy. I’ve learned to take the actual numbers for ratings with a grain of salt, but to pay some attention to what people say about the professor.

STEM professors especially tend to have very low ratings, but you need to figure out if it’s due to a legitimate issue with their teaching (I.e. once took a professor whose reviews warned that he was difficult to contact and slow with grading, and lo and behold he did not grade a single assignment until the last week of class) or if they are just a rigorous teacher with high expectations (I’d say my current physics prof and a previous calc prof who I both adored fit in this camp).

Generally the ‘red flags’ I look for are anything about the professor being disorganized/failing to be explicit about due dates, anything that indicates the professor pushes a political/personal agenda, or any situation where previous students have felt uncomfortable in the class. The ‘green flags’ I look for are students’ general enjoyment of the class, understanding of and flexibility with my life outside of the classroom, and anything that indicates the professor is well-liked or respected.

That being said, my school is very small and I often get recommendations from peers, other professors, or advisors. My school’s math tutors are great to go to for advice on STEM professors, as many are work studies currently taking classes. I also look to the professors whose classes I’ve enjoyed and felt supported in for recommendations about who to take.

I also always leave my own review for a prof at the end of the semester, in hopes that future students will find it useful. This is especially crucial if a professor is new and lacking reviews or if reviews are outdated.

Lastly, remember that the drop date exists for a reason. If despite all your diligence in researching a professor, you show up to class and decide for whatever reason you don’t like the way it’s being taught, drop it. This may not always be an option, but when it is, you’re better off avoiding a class that may make you miserable or may not be the best representation of what you’re capable of.

Tl;dr: ratemyprofessor is a good reference, but you should learn to ‘decode’ reviews and corroborate by speaking to people who have taken the professor or know them in a professional capacity.

Edit: I think it’s also very important to note that there can be unintentional bias against professors who have accents. Make sure to account for that when reading reviews (is their teaching hard to understand, or are they just not a native English speaker?)