NEW YORK (MainStreet) — In response to the 2013 Nielsen Trust in Advertising study, 68% of the 29,000 people polled said they trust consumer opinions they read online. This made user reviews posted online the third most trusted advertising source – behind word-of-mouth recommendations and advertising on branded websites.

Clearly, most of us are reading – and relying on – what other consumers say before we decide on everything from a bottle of shampoo to bedroom furniture, but should we?

"We're in such a peer related society right now. Finally consumers have this voice and it is a good thing," says Stormy Simon, president of Overstock.com. But that doesn't mean everyone is honest. Fake reviews, whether posted by the manufacturer, an irate former customer or a paid reviewer are everywhere online. The key to making informed buying decisions is knowing the difference.

Verifying Reviews

When it comes to weeding out the fakes, you may be on your own for the most part. Policies for detecting and removing fraudulent reviews are up to the individual site.

"We don't want to censor what folks are saying," said Overstock's Simon. "[Overstock] does moderate reviews to make sure there is no foul language, the review is applied to the right product, and if the customer put in any personal information. We're not moderating whether you like it or not."

Yelp, on the other hand, uses an algorithm to spot trumped up reviews. On Yelp's official blog, the company claims about 25% of submitted reviews never make it to the site through this algorithm.

And Amazon.com gives customers the option to mark their review as an "Amazon Verified Purchase" if they bought the product through the site. However, customers can also write reviews for products they purchased elsewhere.

But none of that can guarantee what you're reading is real.

Instead, "you have to stay vigilant," says Bonnie Patten, executive director of TruthinAdvertising.org, and do your own detective work.

Aim for High Numbers

It can be hard to tell if a review is fake if you only have three or four reviews to go on. Start by looking for products with high numbers of reviews, especially if you're shopping for similar items like clothing or shoes.

"The more reviews the better," says Simon. When you're considering a product with a large number of reviews, it will be easier to determine what's real and what isn't. "The wisdom of the crowd will won't let [fake reviews] sustain," she says.

Always Compare Both Sides

Faked reviews can go both ways. Someone may be paid to write an overly positive review of a product, while someone else may fake a negative review to give a company bad press, but odds are good you won't see both happening at once.

To get a feel for which side might be fake, "look at the most positive and the most negative reviews," Patten says. Chances are, one will seem suspicious.

Look for Patterns

Read several reviews for every product you're considering and look for patterns. "If you see a bunch of excellent ratings that could be a sign they are fake," Patten says.

Once you see a pattern, look for the reviews that stand out. If 24 people hated a product and four people loved it, those four reviews could be fake.

Consider Timing

Most review sites include the date when the review was posted and timing can be everything.

"Earlier reviews are more likely to be fake," Patten says. Possibly because the manufacturer was in a rush to build up positive press about the product.

"Lots of reviews posted within a short period of time can also be a warning sign," she says. For example, if a company's employees were asked to post positive reviews, they'd likely post them within hours or days of each other, rather than wait weeks to make their reviews seem more legit.

Good Reviews Tell a Story

A good – and likely honest – review will paint a picture. For example, say you're thinking of buying a tissue box, "If one person is saying this Kleenex box is broken when it arrived but [the company] fixed the problem, they really told a story," Simon says. "That is an honest review."

On the other hand, "some people just write a review that says I love it. Who's to say?" she says.

When you're reading reviews, look for details. Specifics on color, smell or feel can be indicative of an honest review. Longer reviews that include more personal details, such as buying a dress to wear to a specific event, or making a strawberry and banana smoothie in the blender you're considering, are also likely to be true.

Be Conscious of Language

When you write an honest review, you're typically writing from an emotional place - you either loved or hated the product. You're also likely to write like you talk, using slang and personal anecdotes. When a review is fake, the reviewer may not have any actual experience buying the product and the review can feel stiff.

The way the review is written can help you spot the difference. Patten says to look for "reviews that speak in general terms, are heavy on superlatives, and have no specifics or concrete details." Reviews that also lack pronouns like "I" or "we" can also give the reviewer away, according to Patten.

Trust Your Gut

If you're on the fence about a review or two, it may be best to go with your gut.

Simon, who does a lot of shopping online, reads reviews but won't always let a bad review decide what she buys.

"As a consumer, I love [reviews]," Simon says. "Good or bad – I read them and then I make my own decision anyway."

--Written by Angela Colley for MainStreet