This study investigates the consistency of consumer evaluations across mattress types with differing firmness levels. A total of 63 participants evaluated three mattress types twice using a 7-point Likert scale. Intraclass correlation coefficients (ICCs) were calculated to assess test-retest reliability by mattress type. Results showed that firmer mattresses elicited more consistent evaluations, while softer types showed greater variability. To further explore individual differences, inconsistency scores were calculated and used for clustering analysis. Three distinct evaluator types were identified, differing in how their rating consistency varied by mattress type. These findings suggest that evaluation consistency is not a fixed trait of individuals but is influenced by the interaction between product characteristics and the evaluator. The study emphasizes the need for product-specific reliability assessments in consumer research, particularly when evaluating complex sensory products such as mattresses.