Students get angry. I tell students that I will post evaluations and I request that they therefore refrain from obscenity, but with large numbers of students forced to learn in math-hostile facilities, obscenities are inevitable. Should I post [Warning: obscenity-laced] rants anyway? Or filter obscenities out and then post only a biased sample of the more thoughtful criticisms? Rather than fret about the question, I just no longer post evaluations from courses so large that they need to be taught in this format. My teaching evaluations from such classes are mostly hostile, trust me (though a few are accurate).
* The background to the departmental decision is two-fold: improvements in computer aided instruction that allow automatic homework grading; and a long-term decline in permanent faculty.