A city review on Yelp can serve as a kind of meta-review for all the places that a Yelp reviewer might otherwise star (or not). Consider Melissa A.'s two-star take on San Francisco from August:

Here is the inclusive list of locals I met that were not total jerk-faces: the staff at Local Edition; Brandon who works at Tanguito; my server at Denny's; Tom who drives for Bauer's Intelligent Transportation; Miguel, my cab driver on the last night there who called me "meja" and said "mucho gusto" to me as I was exiting his cab; that one nice bartender at E&O Asian Kitchen; the bartender Rye; Mike, one of the captains for Hornblower Cruises & Events; all of the staff and vendors at all the Yelp parties I attended; the local and nearby Yelpers and Yelp staff; the Southwest airlines counter person when I was leaving who was just your average SWA-level of nice who almost made me cry he was so nice.

It's hard to take any Yelp review seriously.

Who knows what the agenda of the Yelper is?

I ignore them all.

Right, the quote above is an example of why Yelp has lost credibility. 

Oh, I see. Good example!