In the old days—say, 15 years ago—consumers checked with friends, family, and consumer reports before making major purchases. Today, they consult online reviews . . . and not just for major purchases. According to the 2011 Cone Online Influence Trend Tracker, 55 percent of consumers do online research after receiving a purchase recommendation for a new car. But nearly 50 percent also do so before selecting a restaurant, and roughly 38 percent before buying footwear or apparel.

The growth of online research puts tremendous pressure on businesses to be viewed positively, leading them to buy positive reviews from consumers or bloggers in order to gain an edge over competitors. Although this might be effective from a marketing perspective, it’s potentially catastrophic from an ethical one. Would you trust a company that hires people to write fake reviews about them? And would you buy from such a company or recommend them to your friends?

Apparently, these concerns aren’t stopping thousands of small businesses from attempting to game Yelp, TripAdvisor, Google+ Local, and other consumer-review web sites. They either commission fake positive reviews or generate phony negative reviews on their competitors. And they’re doing this without considering the ethical implications or the potential negative consequences.

Questions about the legitimacy of consumer-review sites has been building for years. In 2008, Bing Liu, a data-mining expert at the University of Illinois, discovered that 60 percent of Amazon reviews rewarded five stars, with another 20 percent giving four stars, far more positive than a normal distribution curve would indicate. According to the New York Times, book authors used a marketing service—GettingBookReviews.com—to write and place 4,531 phony reviews. Some authors paid as much as $999 to receive 50 reviews of their books. Even more troubling is a recent study by Gartner, a leading technology research firm. The study projects that by 2014, 10 percent to 15 percent of online reviews will be fake and paid for by companies.

One reason why companies are willing to ignore ethical concerns is that online reviews literally make—or break—them financially. For instance, a 2012 study by PR firm Weber Shandwick found that 83% of consumers say online reviews influence their perception of a company, and the Cone study revealed that 80% of consumers changed their minds about purchasing a product or service as a result of reading negative information online. Conversely, 87% strengthened their commitment to buy after reading positive information. What’s more, a University of California study found that a Yelp rating increase of just half a star (on a scale of one to five) increased the likelihood of a restaurant selling out its 7:00 p.m. booking from 30 percent to 49 percent,

So how do you resist the siren’s call to game the consumer-review sites? By becoming aware of the downside risks of doing so. Here are four of them: