Although student evaluation of instruction has been shown to produce reliable results over class averages, considerable within-class variability exists that has not been investigated. This study looked at examples of student evaluations in which students diametrically differed in their evaluation of the same instructor. Patterns were noted. A survey was conducted to determine the self-reported incident of students changing evaluations based on noninstructional factors. About 60% of students admitted that they had changed evaluations for reasons related to the instructor's personality, while 30% admitted to changing evaluations based on grades and rigor. Possible reasons and effects of such changes are discussed.