This study aims to reveal the factors behind students' personal biases and preferences in the evaluation process in order to assess the value of using students' ratings of professors' teaching effectiveness. A questionnaire was completed by 330 students at Lebanese universities asking them to provide their feedback on 23 traits commonly regarded as characteristics of effective teachers. Using factor analysis, four factors were extracted: Teacher's Teaching Skills (F1), Teacher's Leniency (F2), Teacher's Personal Characteristics (F3), and Teacher's Relationship With Students (F4). Results showed that F4 received the highest rating, followed by F1, F2, and F3. Differences in instructor ratings were investigated according to students' gender, class level, major, and GPA. The authors make recommendations for faculty members and administrators based on the results.