[potatolicious]

Not to mention, if I receive something for free my opinion of it is likely higher than if I paid for it.

Case in point: the Motorola RAZR that I inherited a while back. It's a solid enough phone, got the right features, and for free it's very damned good!

But charge me $100 for it and watch my review go the other way.

Even without the arguably malevolent notion of positive-reviews-for-more-swag, the mere fact of receiving something for free likely induces a more positive review.

[jbischke]

Yeah, I was looking at ~$250 products that had tons of Vine reviews. If you're getting something worth $250 free to keep I gotta thing that's going to affect how you review it.