Instruct: Classify a given Amazon review as either positive or negative.
Query: Not sewn correctly

I've enjoyed wearing Rainbows for years, and was happy to find a great price on Amazon. However, the inside of the strap was sewn incorrectly and caused blisters, to the point I had to remove them and walk barefoot. Amazon's return policy was easy, but these were inferior quality and should never have been sold as new. Could be a quality control problem, or this vendor is selling seconds as the real thing.