When good product reviews are bad news for business


Customer reviews are a very important source of information for buyers when it is difficult to evaluate or test a product before purchase, as in the case of online purchases. Positive reviews can amplify sales by as much as 0.149, and is particularly relevant for high financial risk decisions, services, hedonic products, and new products.


However, research shows that very positive reviews can actually have a detrimental effect. Where is why.


The boomerang effect

Research by Reimer and Benkenstein* showed that some highly positive reviews can actually reduce sales, whereas highly negative reviews can increase them. This ‘boomerang’ effect happens when consumers think that:

  • the writer of the review has vested interests and, thus, is not trustworthy;
  • the arguments provided are not valid. For instance, when the review is not meaningful, is not informative, does not contain enough arguments, or does not provide good reasons to support the assessment.


Implications for marketers:

  • It is important to provide trustworthy reviews. If you manage the review platform, try to ask reviewers for detailed recommendations (for instance, via filters and review menus), and design mechanisms that reassure website visitors that these are genuine reviews.
  • Positive reviews that are seen as untrustworthy can backfire. If you manage the review platform or are displaying reviews on your website, give more emphasis to positive reviews with good argumentation (e.g., show them first);
  • Negative reviews that are seen as untrustworthy may not hurt your sales, at all. Hence, when responding to negative reviews, consider highlighting the poor argumentation used or, if relevant, the untrustworthiness of the reviewer.



The disconfirmation effect

Research by Minnema and colleagues** found that overly positive online reviews are associated with high levels of product returns. The authors say that when people buy a product based on very positive reviews, they have inflated expectations about the product. These expectations are not confirmed when the product arrives, thus leading to disappointment and product returns. This is problematic for online traders because the logistics costs of handling product returns can dent their profitability. This ‘disconfirmation’ effect is strongest for:

  • Consumers with limited experience of buying from this online retailer;
  • Cheaper products***


Image source

Implications for marketers:

  • It is important to set the right expectations. Try to get and display a broad range of reviews on your site.
  • Information that gives an accurate description of the product is likely to reduce disappointment post-purchase. Hence, when encouraging consumers to write a review, suggest a range of factors that provide a good representation of the product’s performance.
  • The disconfirmation effect is stronger for new customers. Consider providing additional information to customers that helps them decide whether the product is suitable for them (e.g., a checklist, or infographic), and which helps them make the most of the product (e.g., links to free video tutorials).


There you go. Some online reviews are so good… that they turn out to be bad.


Did you experience the boomerang or the disconfirmation effect yourself?




* in the context of restaurant reviews

** in the context of electronics and furniture reviews

*** the authors reason that expensive products are risky and, thus, consumers do extensive research before buying the product, which offsets the impact of an overly positive review

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