There was a feature on NPR recently about how businesses are being attacked on sites like this. The example they sited was a wedding dress place that had a lot of positive reviews and then more recently a lot of negative reviews. They found out most were from the same computer. The clues are extreme opposite reviews (lots of 5 star and lots of 1 star), a similar style of writing, similar words, lots of reviews submitted the same day, etc. Seems to be whats going on here.
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