I bought some headphones on Amazon that came with a note offering a $10 refund if I left a 5-star review. I didn't. But several months later when I decided to leave a real review, I found that the product was no longer listed. But an identical product was now sold from a vendor with a near-identical name as the previous vendor. Digging deeper, I see that they even had another different name before I even bought it.

So that's at least 3 different times that this vendor has boosted their reputation and sales by paying for reviews and then switcheroo'd after things slow down.

Meanwhile Amazon happily collects its fees and doesn't give a damn.