In short: Is a 5-star rating suspicious? Not in itself, but it deserves a second look. Studies show that purchase likelihood is highest at 4.0 to 4.7 stars and falls again towards 5.0, because customers consider perfect scores too good to be true. What matters is the number, the age, and the content: a 5.0 built on a few short reviews says little, while a 5.0 built on many detailed experiences can be genuine.
Here is a finding that surprises many business owners: in none of the product categories examined was the optimal average rating – the one with the highest purchase likelihood – 5.0. That was the conclusion reached by the Spiegel Research Center at Northwestern University in the full version of its report. The perfect score that so many aim for is evidently not the optimum from the customer's point of view.
That does not mean every 5.0 profile is faked. It does mean that readers instinctively become skeptical – and that it pays to ask the right questions.
At what star average are customers most likely to buy?
Several studies arrive at a similar picture: willingness to buy rises with the average, but not all the way to the top.
| Study | Key finding | Year |
|---|---|---|
| Spiegel Research Center | Purchase likelihood peaks at 4.0–4.7 stars and falls towards 5.0 | 2017 |
| PowerReviews, together with the Spiegel Research Center | Purchase likelihood highest at 4.2–4.5 stars; 82% specifically look for negative reviews | 2015 |
| Hu, Zhang & Pavlou | Reviews follow a J-shaped distribution; the average is a weak indicator of quality | 2009 |
| BrightLocal (USA) | Only 10% consider exclusively 5-star businesses; 68% expect at least 4 stars | 2026 |
The Spiegel Research Center explains the effect by noting that customers perceive scores at the very end of the scale as "too good to be true". In the summary of its report it names a narrower window of 4.2 to 4.5 stars. PowerReviews, which conducted the study together with the Spiegel Research Center, names the same range.
PowerReviews' second finding is striking: 82% of shoppers specifically look for negative reviews, and among the under-45s the figure is 86%. Customers want to know what can go wrong. If there is no criticism at all, they lack that information – and mistrust grows.
❌ Myth: "The closer to 5.0, the better for business."
✔ Fact: According to the Spiegel Research Center, purchase likelihood peaks at 4.0 to 4.7 stars and falls again towards 5.0. A few critical voices make a profile more credible, not weaker.
Why are so many reviews so positive in the first place?
Anyone who looks through a lot of profiles notices quickly that four and five stars dominate almost everywhere. That is not necessarily down to manipulation, but to a well-known statistical pattern.
In 2009 the researchers Hu, Zhang and Pavlou described the J-shaped distribution of online reviews. For books, DVDs, and videos on Amazon, 78%, 73%, and 72% of reviews respectively were four stars or more. On top of that there is a small bump at one star, with hardly any reviews in between. The reason: it is mainly very satisfied and very annoyed customers who write, while the moderately satisfied stay silent. The authors conclude that the average is therefore a weak indicator of actual quality.
For interpretation that means: a high average is normal. It only becomes suspicious when the distribution consists exclusively of fives and other features come on top of that.
How much does a 5.0 average based on few reviews tell you?
Very little. According to its own help pages, Google calculates a business profile's rating as the average of all published ratings. With three reviews, then, three satisfied customers – regulars or acquaintances, say – are enough for the perfect score. Add a single one-star rating and, with four reviews, the average drops to 4.0.
Volume has an effect of its own. According to the Spiegel Research Center, purchase likelihood for a product with five reviews is 270% higher than for one with no reviews. After that, the added benefit of further reviews falls off quickly. In BrightLocal's 2026 US survey, 47% also said they would not use a business with fewer than 20 reviews.
When is a perfect average genuine – and when is it suspicious?
A 5.0 can be entirely legitimate, for instance at a small business with loyal regulars or at a new practice that has only just started collecting reviews. The comparison below helps with interpretation.
✅ Points more towards a genuine 5.0 average:
- Reviews are spread evenly over months or years
- Texts name specific services, staff, processes, or problems that were solved
- Reviewer profiles have rated other businesses too
- Other platforms show a similar, if not identical, picture
- Reviews come from verified customers
❌ Points more towards caution:
- Many reviews within a few days, then a long silence
- Short, interchangeable texts such as "Great, would come back anytime!"
- Reviewer profiles with only a single review
- Clearly worse scores on other portals
- A conspicuous absence of any criticism despite a large number of reviews
None of these features proves manipulation on its own. Only the accumulation makes a profile suspicious. You will find all eight typical warning signs in detail in our guide on how to spot fake reviews. How much a check mark next to a reviewer is worth is explained in the article What are verified reviews?.
💬 Expert view: "A 4.6 profile with criticism answered factually convinces me more than a flawless 5.0. The replies show how a business works when something goes wrong." – Lars Hermes
What does this mean for companies with a perfect average?
For business owners the message is reassuring: the first four-star review is no disaster. It can even make the profile more credible. Anyone who instead tries to hold on to the perfect score by any means necessary – by asking only satisfied customers, say, or by buying reviews – risks platform sanctions and legal trouble. Our guide Is it legal to buy reviews? shows why buying is not an option.
A steady stream of genuine reviews, which lets the average settle naturally, is the better route. Our guide on getting more Google reviews describes how to achieve that legally.
Conclusion: The perfect average is not the goal
A 5.0 average is no proof of fraud, but it is no promise of quality either. The research shows that purchase likelihood is highest at 4.0 to 4.7 stars (at its core 4.2 to 4.5), because scores like that come across as realistic. Whether a perfect average is genuine is revealed by the number of reviews, their distribution over time, the level of detail, and the comparison with other platforms – not by the figure itself.
So make it a habit never to look at the stars alone. Compare a company's reviews across several sources, for example through the reviewfinder directory, which bundles reviews from different portals.
Frequently asked questions
Which star rating is good?
Studies see the highest purchase likelihood at 4.0 to 4.7 stars, and especially between 4.2 and 4.5. In BrightLocal's 2026 US survey, 68% of consumers expect at least four stars and 31% at least 4.5.
Are 5-star reviews on Google often faked?
Not across the board. Many 5.0 profiles belong to small businesses with few, genuine reviews. At the same time, Google says it blocked or removed more than 292 million policy-violating reviews worldwide in 2025 – across all reviews. A perfect average is therefore no proof of manipulation, but it does justify a closer look at the number of reviews, the timing, and the texts.
How many reviews does an average need in order to be meaningful?
There is no fixed threshold. According to the Spiegel Research Center, purchase likelihood rises sharply with the first five reviews alone. For a robust assessment, however, considerably more recent reviews help. In the BrightLocal survey, 47% avoid businesses with fewer than 20 reviews.
