It may be a new year, but there are still problems with Yelp’s review filter. We’ve been tipped to some research finding reviews featuring promo codes, which would seem to violate Yelp’s guidelines, showing up for Uber and Lyft, as well as a competing taxi service. Yelp’s filter has long been the subject of controversy with small business owners, and these findings highlight yet another issue with it.

Are you happy with Yelp’s review filter? Do you think it does a good job of eliminating spam? Let us know what you think.

“We conducted some research that found many customers of Uber are spamming Yelp’s review in order to promote their promo code. These codes work as an affiliate program so whenever a new customer uses the code, then the person gets $5 in Uber credit,” Strategy Response tells WebProNews in an email. “In smaller markets, most of the 5-star reviews for Uber are clearly biases as they are promoting a code. These codes allow the person to receive credit when someone else uses their code.”

These promo codes got some attention last year when celebrities like Lindsay Lohan, Snoop Dogg, and Neil Patrick Harris were promoting their codes on social media.

As Strategy Response notes, such a conflict of interest on the part of reviewers is a clear violation of Yelp’s guidelines. This is what Yelp actually says under the “Conflicts of interest” section:

Your contributions should be unbiased and objective. For example, you shouldn’t write reviews of your own business or employer, your friends’ or relatives’ business, your peers or competitors in your industry, or businesses in your networking group. Business owners should not ask customers to write reviews. Emphasis added.

While this sort of thing might be fine on a platform like Twitter, Yelp is a different animal. It has direct influence on whether or not people use a business. That’s the whole point. It’s easy to see why reviews with these promos would be a violation of Yelp’s guidelines. They’re obviously biased. The problem is that the filter isn’t doing its job in eliminating them.

Strategy response found examples in a variety of cities across the U.S. In Louisville, there’s only a single review for Uber, and that review gives the company a five-star review and includes a promo code.

The same goes for Kalamazoo. In Charleston, 3 of the 4 reviews include a promo code. In Des Moinses, 2 out of the 3 reviews promotes a code.

You can see an example for Lyft in Raleigh-Durham here.

Yellow Cab in Austin, which has a one-and-a-half star review, displays this review promoting an Uber user’s code:

So this is also something that could potentially have an impact on competition.

“We believe that this is a serious issue as it brings into question Yelp’s filter,” Strategy Response tells WebProNews, noting that in many of our previous articles about Yelp, readers mentioned their frustration and anger with Yelp’s ‘recommended reviews’ section. “Also, Uber is gaining an unfair competitive advantage from an artificially higher Yelp review based on these biased reviews. A Harvard study found that restaurants are able to get a 5 to 9 percent increase in business based on an increase of one-star on Yelp. With some markets only have a single 5 star review for Uber based on a reviewer promoting their own code, this gives them an unfair advantage that Yelp has been unable to address.”

In its report, Strategy Response says:

What we do want to highlight is that Yelp’s filter system is not perfect. These reviews got through the filter, and once they were posted, it appears as if there were no further quality control investigation by Yelp. There has been many articles written about Yelp’s filter. If you have a small business, you have probably express anger, frustration, and fear when the filter prevents customers from leaving a glowing review. However, in addition to worrying over your own profile, it is also very important to check your competitors profile to see what has gotten through. In these examples, the competing taxi companies and ride-sharing apps in these markets should have flagged these reviews to get them removed. Regardless of the true intentions of the reviewers, the fact that it included a promo code should have prevented them from being displayed.

Last month, Yelp launched a new app for business owners aimed at enabling them to better manage their Yelp reputations and respond to consumers more quickly. Based on our reader response, businesses aren’t very impressed.

Do you think Yelp’s filter is adequate, or is it detrimental to businesses? Share your thoughts in the comments.