Brands know that customer reviews play an integral role in consumers’ purchasing decisions, especially online. As such, they work hard to drive the highest ratings they can. And yet, it’s the presence of less-than-five-star reviews that can actually be what drives purchase.

Recent data analysis across 40 product categories looked at the impact of reading reviews on purchases. Northwestern University’s Spiegel Research Center and PowerReviews found that, in moderation, bad reviews actually help boost sales.

In fact, product purchases were most influenced by reviews with an average star rating between 4.2 and 4.5, according to research from GetApp. Products with five-star ratings were less influenced, likely due to today’s skeptical consumers’ “ too good to be true” sensibilities. Having a few less-than-perfect reviews decreases a product’s average star rating, but grows the business more.

Why are five-star reviews too good to be true? We think it’s authenticity.

There’s a healthy cynic in us all. We know nothing is perfect. So when a consumer sees only five-star reviews, they smell something fishy, something that causes their BS meter to go off.

They know that some negative opinions about a product, service or place are to be expected, and become suspicious when something is marketed as “perfect.” And as Amazon recently filed a lawsuit against more than 1,000 sellers of fake four- and five-star reviews, consumers are scrutinizing reviews more closely than ever before — and have reason to do so.

A mix of good and bad reviews demonstrates a brand’s transparency.

Healthy skepticism is growing for advertising, journalism and, so too, for perfect product reviews. A mix of good and bad reviews demonstrates a brand’s transparency, and may well signal that the reviews displayed on your website are not fake or filtered. In fact, some shoppers might go so far as to ignore brands or products with only five-star reviews and look for a more genuine alternative.

While it’s important to include a mix of star ratings, it doesn’t mean brands shouldn’t emphasize top reviews. Consider the following practices:

Offer (and test) options

Offer several options for reading reviews, from highest to lowest star rating or by ranking those as most “helpful.” This same strategy can be used for product offerings, your blog and other content. Include several options for current and potential customers to find the information they seek; customers are always receptive to a more personalized experience.

Value the content

The content of the reviews is another influencer of purchase behavior. When consumers read the review to find out why the product received a specific rating, what may appear to be a negative review can prompt a purchase.

For example, if a product has a four-star rating instead of five because the reviewer thinks it’s “not the right shade of red,” it may be just the message to prompt another purchaser to buy.

Keep negative reviews and pay attention

Eighty-two percent of consumers specifically seek negative feedback, so it should be made available to customers. As our research reflects, maximizing the value of customer reviews to drive purchases demands the presence of less-than-five-star reviews. Also, while brands seek ways to improve their product or service offering, fewer than five stars provides authentic and valuable insight to make strategic improvements.

Our research revealed that, in some categories, reading a review can not only have an impact on purchase, but a dramatic one. So, to make consumer reviews matter most to consumers, it’s important to encourage all reviews, avoid hiding negative ones, offer customers the opportunity to expand on their reviews and act on customer reviews based on specific feedback.

The consumer is expecting the brands they choose to not just offer a great product, but to listen, respond and, per our research, stay authentic.