RMP is like the Jose Canseco book that threw several baseball players under the steroids bus — the information provided is somewhat factual, but the source’s credibility weakens the message.
Incompetent (boring, can’t speak English, vague grading standards, etc.) professors get low ratings on RMP, but friendly professors get good ratings regardless of how effectively they teach. I can attest to that, because my ratings and comments have not changed much as I’ve moved from school to school, even though my teaching is much more mature now than it was when I started as a graduate student.
Another problem with the site is that it gives low ratings to the professor who likes to mark papers up with red pen and who doesn’t hand out trophies just for showing up to the game. Such teachers can have a positive and lasting impact on students.
Yet there is nothing inherently wrong with RMP. If students want to share personal opinions on professors, they’re free to do so — they have done that for eons. Problems arise when other stakeholders use the information on RMP to suggest that these students’ opinions of professors are anything other than a data point for 360-degree feedback.
Dare I say that students don’t always know what is best for them and that professors need to maintain their authority in the classroom to teach effectively?