I'm late to this thread, but I met a restaurant owner in Barcelona who said TripAdvisor employees demanded to have lunch for free in exchange of good ratings.

I'm late to this thread, but I met a restaurant owner in Barcelona who said TripAdvisor employees demanded to have lunch for free in exchange of good ratings. He declined and got bad ratings. He also got a visit from Yelp, that didn't demand anything in exchange for listing his business.