Like most people, you probably read customer reviews before you buy something online. In fact, 95% of people say that reviews are helpful when making purchasing decisions.

Realizing this, some sellers (and even major brands) have begun writing fake reviews – either to make their own products look better or to discredit their competitors. In fact, one study found that 31% of reviews left on Amazon, Walmart and BestBuy were fake.

So how can you spot these fake reviews?

Use a review checking service

Websites like ReviewMeta and FakeSpot use advanced language analysis to assess whether reviews are real or fake. Simply paste the URL for a product and click ‘Analyze’. Both of these sites provide a score indicating how many ‘suspicious’ reviews have been written. You will also see a warning if the product has received a high proportion of fake reviews.

ReviewMeta and FakeSpot are optimized for use with Amazon, but they can also grade many other popular shopping sites. Unfortunately this does mean that not every site or product can be analyzed in this way.

Don’t just rely on stars

You’ll notice that many products have been rated 4.5 stars or higher. Sometimes this indicates a truly great product – other times it is evidence of fakery. Take time to read some of the reviews, particularly those of average or lower scores to try and get a balanced cross-section of what people are saying.

Use your common sense

Very short reviews (‘Great!!’, ‘Excellent product’, ‘Love this item’) aren’t very helpful. There is also a high chance that these reviews are fake, used to boost the star rating of the product.

Again, take some time to read other, longer reviews that provide more information about the product and the customer’s experience.

Read professional reviews

Customer reviews can sometimes be limited by the writer’s lack of experience. Say you want to buy a camera; the customer reviews are usually written by someone with very limited experience of cameras – in fact they may have only ever used that one device. A camera expert will have worked with many cameras however, allowing them to give a more detailed description and to compare between devices to help you make a smarter choice.

Because of this, expert reviews are particularly important when making high value purchases.

Check the reviewer

When considering reviews, take a moment to check out the reviewer themselves. Have they written many reviews? Have they written a lot of reviews in a very short period of time? Always be wary of accounts that have only ever written a single review. And reviewers who write lots of evaluations in a short period are very likely to be fake.

If you can’t trust the person writing the review, you can’t trust what they have written.

Just like when dealing with malware, your best protection against fake reviews is to keep your wits about you. These five tips will help you spot a fake review – and avoid falling victim to scammers.