Eric Strand, in a tongue-in-cheek article about RateMyProfessor.com says his negative experiences with this anonymous rating source has "created a teacher who is going to make sure his students sweat for their A's and B's. The hardworking students (and there are plenty of them) will not have a problem with that, but a few others will resent me...And that's fine." While I'm not sure that revenge is a good reason to set high expectations, he does go on to say that the professors he would like to emulate aren't "afraid to unsettle the students, and they weren't so concerned with whether the students liked them."
My advice: Don't give RateMyProfessor any credibility by reading it. The good comments you probably already know. The negative ones will not give you any feedback that is useful or contain information that can help you improve your teaching. Instead, as noted by one professor in discussing his student evaluations, "I get great evaluations - but all it took was one to crush me. One student who didn't "get me" and my teaching style and I find myself becoming bitter and angry towards all of them...one student to write into RateMyProfessor.com with a snarky comment about me to make me question my choice to be a university prof."
Why would we give one disgruntled student that much power?