Many of us use online reviews to judge products but Mike Essex (right), online marketing manager at digital marketing agency Koozai, says they are open to abuse.

Don't believe everything you read, especially if it's a product review.

While they are a great way of finding out what's worth buying, they are also ripe for manipulation with people offering to write fake reviews about brands for as little as 50p.

Here are a few examples:

  • Online forum has over 160 listings of people offering to write positive reviews on Amazon, without ever having tried the product. Worst of all, there are people offering to write negative reviews, for companies who want to damage a competitor's reputation.
  • Amazon's Mechanical Turk, a website offering quick jobs, has paid jobs for writing reviews. One I've seen requests a positive 5-star review about a computer company's products for around 50p a time.
  • Hotel review website Trip Advisor has come under scrutiny for everything from hotel staff writing positive reviews to hotels offering customers discounts if they write glowing reviews.
  • Even products that haven't been released yet have reviews. The DVD for Torchwood Miracle Day isn't due for release until 14 November, nor has the show finished on TV, yet it has amassed 23 reviews. Although these reviews may not be fake, it highlights just how easy it is to leave a review.

The problem stems from a lack of proof. You can write a fake review on Amazon and Trip Advisor without having purchased a product. This has even led some customers to leave joke reviews for products to highlight how easy it is to manipulate the system.

It illustrates a need for tighter controls all around.

I should point out that where ads appear on online forums the forum owner itself is not to blame.

The fight back

Trip Advisor has been plagued with fake reviews since its origin, and it is one of the few companies that actively fights back. It displays a red warning at the top of any hotel that it feels has been writing fake reviews.

It's a good concept, and a quick search reveals 18,000 pages on the Trip Advisor website that have been marked in this way.

Nevertheless, it's worrying to see so many hotels engaging in this practice, especially as many are small hotels. It is a major problem.

The Trip Advisor solution is reactive and as such can only protect you if it catches a fake review before you read it. Instead, it's up to consumers to protect themselves.

What to do

Don't just trust the reviews on one website. Instead, search for the product you want with the word "review" in a search engine. If lots of websites have positive reviews, there is a higher chance it is good.

Many industries have websites that compile reviews from reputable sources, such as the mainstream media. These have a higher level of trust, and should always be the first place to check.

For example, with films, there's Rotten or for video games, Game These sites should appear when you do the above search, so keep an eye out for them.

The best thing Amazon ever did to its reviews was to let customers say if they found a review useful. Each review will say above it "X out of Y people found the following review helpful".

This allows the users to police fake reviews. So if you spot a review that looks too good to be true you can mark it as such, and warn other users.

Click on the name of a reviewer to see what else they have reviewed. If they have only reviewed one product then don't take their word as gospel. Look for people who have left a good mixture of reviews, with positive and negative comments.

More help may be on in future. Researchers are working on software that will spot negative reviews online based on the grammar used.

Until then, carry on reading reviews, but consider the above. If all else fails, and the product is terrible, leave your own bad review.

Views expressed are not necessarily those of