When I saw that Sephora had added a new product that promised to smooth out otherwise unfixable acne scars in eight weeks, I was intrigued but not entirely convinced. When I saw it had already racked up close to 200 five-star reviews, I grabbed my credit card.

But my excitement was tempered nearly all of those reviews had a small disclaimer beside them: Received free product.

The reviews were not written by those who spent their own money on the product, but rather by those who had been given the product in exchange for a review.