RateMyProfessors.com (RMP) is the most popular commercial website to evaluate instructors, and houses a wealth of student-generated information in the form of ratings and reviews. This study investigated whether general chemistry students who use RMP were different from other students, and their reasons to use and contribute to the site. A pool of 398 students were surveyed. The survey gathered demographic information, patterns and frequency of use, and information to characterise participants in terms of their learning/grade orientation. Data analysis included descriptive and inferential statistics and the application of mixture models (latent class analysis and latent profile analysis). There were no significant differences between contributors and non-contributors in terms of gender, major, year status, grade point average, course load, previous chemistry grade and learning/grade orientation. Findings for this sample do not support the common assumption that students use RMP to shop for easy instructors. Instructor helpfulness, clarity and overall rating were reported as important aspects to visit the site. Findings agree with literature reports and support the use of RMP as supplemental data to inform assessment of instruction at the general chemistry programme level. Programmes in other disciplines can adapt the methods presented to assess the suitability of RMP data-sets for similar purposes.