User reviews are an established part of the online shopping landscape. And so it comes as no surprise that companies have tried to "game" the system to their advantage. It also means reviews from actual consumers can be up for sale, undermining the entire process.

The New York Times reported this week that Amazon took a merchant off its site because it was offering a full rebate on $10 leather cases for the Kindle Fire if the buyer wrote an online review. The merchant, VIP Deals, shipped the Kindle cases with a letter that offered the rebate.

"Advertising disguised as editorial is an old problem, but it's now presenting itself in different ways," the Federal Trade Commission's associate director for advertising practices, Mary Engle, told the Times.

Here are some tips for spotting fake product reviews from LifeHacker, by knowing some key words that can point toward fake reviews:

• Overly enthusiastic language and an abundance of exclamation points: "Really very happy with the awesome (insert product name here)!!
• Use of, and reliance on the first-person singular, and references to people the reviewer was with, such as "my wife, or, "my family."
• Exact and perhaps unnecessarily specific product name, details or location, especially if repeated more than once. Legitimate reviews are more likely to use more vague language since it is already apparent or established what product or service is being discussed since the review is already attached to the product page.

For $2 a Star, an Online Retailer Gets 5-Star Product Reviews [New York Times]
Detect Fake Online Reviews by Knowing the Right Words to Look For [LifeHacker]