> You've got stores that would include a $5-$20 coupon/gift card in the item in exchange for a positive review.

I had a tool manufacturer read a bad review on one of the big box home improvement stores in the US, they contacted me within a day (the store must have gave them my email address?) and offered to send me my choice of replacement tool, for free, in exchange for taking my review down.

Helps me learn which companies not to trust.