I also feel there is inherent conflict of interest when users post negative reviews at sites like Seamless, Grubhub, AirBnB, VRBO etc. As these companies receive revenues from their partners they might be biased against negative reviews. It would be interesting to see some statistical analysis between reviews on Yelp and reviews on these sites on the same merchant (restaurant, property manager etc.).I would not be surprised if the analysis shows that some of these sites have an artificial upward bias in their reviews/ratings.