A group of University of Melbourne economists have looked at what drives student evaluations of subjects other than lecturer quality. In Australia, cultural background is a big factor. The abstract to the paper is over the fold. 

In this paper we examine 8 years of Quality of Teaching (QOT) responses from an Economics Department in an Australian University. This is done to determine what factors besides the instructor have an impact on the raw average student evaluation scores. Most of the previous research on student ratings has been conducted in the United States. One significant difference between US and Australian tertiary education is that on average the number of foreign undergraduate students is 10 times the number in US institutions. We find that cultural background significantly impacts on student evaluations. Other factors that have an influence on the average QOT score include: year level, enrolment size, the quantitative nature of the subject, gender of the students, their fee paying status by gender, their course of study, the differential in their mark from previous marks, quality of workbook, quality of textbook and the relative QOT score versus other subjects taught at the same time. In addition, the average of QOT scores after instructors have taught in a mix of subjects gives similar results to adjusting the QOT scores to account for subject and student characteristics.