Online consumer reviews are a convenient, valuable pool of information for potential buyers as well as for marketers. But how reliable is this information? A closer look at the motives behind posted product reviews shows that online opinions should indeed be interpreted with care. The study results reveal that the composition of the customer base can exert a substantial influence on the posted online opinion. Due to selection bias and adjustment effects over time, the content posted may not necessarily reflect the customer base’s overall opinion of the product. Individuals were more likely to submit ratings when they were either very satisfied or not satisfied. In addition, consumers were more likely to post an opinion when the ratings already posted were more positive. Highly engaged consumers who frequently post their opinions tend to be more negative than less-engaged individuals. Even though decision-makers can gain valuable insights from the analysis of this pool of information, they should not rely on this source exclusively.