College students critique their professors' teaching at RateMyProfessors.com, a web page where students anonymously rate their professors on Quality, Easiness, and Sexiness. Using the self-selected data from this public forum, we examine the relations between quality, easiness, and sexiness for 3190 professors at 25 universities. For faculty with at least ten student posts, the correlation between quality and easiness is 0.61, and the correlation between quality and sexiness is 0.30. Using simple linear regression, we find that about half of the variation in quality is a function of easiness and sexiness. When grouped into sexy and non-sexy professors, the data reveal that students give sexy-rated professors higher quality and easiness scores. If these findings reflect the thinking of American college students when they complete in-class student opinion surveys, then universities need to rethink the validity of student opinion surveys as a measure of teaching effectiveness. High student opinion survey scores might well be viewed with suspicion rather than reverence, since they might indicate a lack of rigor, little student learning, and grade inflation. (Contains 8 tables and 4 figures.)