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Apparently, Grayboxx is trying to solve the problem of user reviews only being viable in a few business classifications. They are using several data sources, including anonymized personal email, to spot references to local businesses in around 4000 business categories.
The system is US orientated so I don't know how reliable the scoring system is. Maybe some of our US members can let us all know how good the results are in their area.
They are also very coy about their system, referring to "Graybox gets this data from a variety of third-party vendors" - so it's hard to know what level of paid-for promo is built into the system.
GB will have to monetise somehow, and my bet is on 'sponsored listings' - the only question is how clearly these are labelled.
Time will tell.