Despite their widespread use, contingent valuation (CV) studies have long faced serious criticisms regarding the reliability and validity of their results. The hypothetical nature of scenarios, reliance on stated preferences, and absence of actual market behavior introduce various types of biases in the design, implementation, and analysis of these studies. Such biases imply that merely applying the CV method without carefully evaluating data quality is often considered unacceptable by many researchers and journal reviewers. In response to these challenges, there has been growing attention to assessing the reliability and validity of CV studies. Although the literature emphasizes the importance of these concepts, reviews indicate that in many empirical CV studies, reliability and validity tests are either limited or reported only descriptively. Accordingly, the present study aims to identify and explain different types of biases in CV studies and to examine the reliability and validity tests conducted. To provide a practical example, various validity tests from a previous study by the same author, which applied the CV method to estimate the use values of Lake Avidar in Nowshahr County, were reviewed. The results indicated that content validity, construct validity, and expectation-based validity were relatively high, whereas convergence validity was somewhat low.