Reviews are the lifeblood of companies selling on Amazon. Bad reviews or few stars can kill a product.

It's so important some companies pay people to set up fake Amazon accounts to leave fake customer reviews. But it's hard to weed out the fakes from genuine reviews.

There are two websites that can help. One is Fakespot, and the other is Review Meta.

You simply copy and paste the Amazon link to the product in a search bar on those websites. Fakespot and Review Meta use algorithms to find the phonies.

I tried it on a wireless security camera. It has nearly 1,700 four-and-a-half star review, but Review Meta looks for common words in the review such as "easy to set up". It also found that 14 percent of reviews came from "one hit wonders." They've only reviewed this product.

Review Meta believes there are 800 fake reviews, bringing the score down to four stars. But that's nothing compared to the reviews for a pest repeller with a four-and-a-half star rating. Using the same algorithm, Review Meta dropped it to 1.8 stars.

Amazon claims it removes fake reviews and that only 1 percent of reviews are fake. Even if that's true, there are 48,000 fake reviews floating around out there.