If there were ever a reason to take Yelp reviews with a grain of salt, it’s the flood of new postings about Big Apple Pizza in Fort Pierce, Fla. The small pizzeria gained national attention this week when President Obama visited and the owner, Scott Van Duzer, lifted the commander in chief off the ground in a widely photographed, Secret-Service-cleared bear hug.

As the photo spread across the Internet, reactions started appearing on the user-review website. First came the one-star reviews, some laced with ugly commentary, many removed by Yelp editors. Then came the five-star counterattacks. Within a day, the restaurant had drawn more than 2,500 new postings, many of which had only tangentially to do with the quality of the pizza.

When it comes to online reviews, it’s clear that the buyer must beware. The proliferation of planted and paid reviews, on websites such as Amazon, TripAdvisor, and Yelp has led researchers to hunt for algorithms to determine what’s authentic and what isn’t. The Big Apple controversy is another wrinkle: proof of how easy it is to hijack a consumer tool, and how hard it is, these days, to escape the noise of partisan bickering. If politics trumps all, something is lost, even if it’s just another way to find the best slice of cheese in Fort Pierce.