On the first hot weekend of the summer, Richard Knapp put up a sign outside Mother’s Ruin, a bar tucked in Manhattan’s SoHo neighborhood. It had two arrows: one pointing vaccinated people indoors, another pointing unvaccinated people outdoors. The Instagram post showing the sign (above) quickly went viral among European anti-vaxxers on Reddit. “We started receiving hate mail through the Google portal,” Knapp says, estimating he’d received about a “few dozen” emails: “I’ve been called a Nazi and a communist in the same sentence. People hope that our bar burns down. It’s a name and shame campaign.” It wasn’t just the emails. Soon, his bar started receiving multiple one-star reviews on Yelp and Google Reviews from accounts as far away as Europe. Spamming review portals with negative ratings is not a new phenomenon. Throughout the pandemic, the tactic has also been deployed to attack bars and restaurants that enforced mask-wearing for safety. As pandemic restrictions have lifted, businesses like Mother’s Ruin have sought to ensure that safety by requiring proof of vaccination using state-sponsored apps like New York’s Excelsior Pass, vaccine passports, or simply flashing vaccine cards at the door — practices that have instigated a second surge of spam reviews. These spam one-star reviews can be extremely damaging. The default mode for viewing reviews is in chronological order, from newest to oldest, which means a spam attack places fake reviews up top, making the most recent reviews that much more influential if you’re the victim of a concerted campaign. While some companies have gotten around this issue on their own sites by verifying that reviewers are actual customers by reaching out to them via email and matching them with what they have on file, industry-leading platforms like Yelp and Google let anyone rate and review a business. Related Story You don’t get an invite to these weddings unless you’re vaccinated or have a negative covid test Couples who can’t wait to get married must navigate a tricky ethical quagmire to ensure the safety of their big day. Smith’s Yelp reviews were shut down after the sudden flurry of activity on its page, which the company labels “unusual activity alerts,” a stopgap measure for both the business and Yelp to filter through a flood of reviews and pick out which are spam and which aren’t. Noorie Malik, Yelp’s vice president of user operations, said Yelp has a “team of moderators” that investigate pages that get an unusual amount of traffic. “After we’ve seen activity dramatically decrease or stop, we will then clean up the page so that only firsthand consumer experiences are reflected,” she said in a statement. It’s a practice that Yelp has had to deploy more often over the course of the pandemic: According to Yelp's 2020 Trust & Safety Report, the company saw a 206% increase over 2019 levels in unusual activity alerts. “Since January 2021, we’ve placed more than 15 unusual activity alerts on business pages related to a business’s stance on covid-19 vaccinations,” said Malik. The majority of those cases have been since May, like the gay bar C.C. Attles in Seattle, which got an alert from Yelp after it made patrons show proof of vaccination at the door. Earlier this month, Moe’s Cantina in Chicago’s River North neighborhood got spammed after it attempted to isolate vaccinated customers from unvaccinated ones. Spamming a business with one-star reviews is not a new tactic. In fact, perhaps the best-known case is Colorado’s Masterpiece bakery, which won a 2018 Supreme Court battle for refusing to make a wedding cake for a same-sex couple, after which it got pummeled by one-star reviews. “People are still writing fake reviews. People will always write fake reviews,” Liu says. But he adds that today’s online audience know that platforms use algorithms to detect and flag problematic words, so bad actors can mask their grievances by blaming poor restaurant service like a more typical negative review to ensure the rating stays up — and counts. That seems to have been the case with Knapp’s bar. His Yelp review included comments like “There was hair in my food” or alleged cockroach sightings. “Really ridiculous, fantastic shit,” Knapp says. “If you looked at previous reviews, you would understand immediately that this doesn’t make sense.” Liu also says there is a limit to how much Yelp can improve their spam detection, since natural language — or the way we speak, read, and write — “is very tough for computer systems to detect.” But Liu doesn’t think putting a human being in charge of figuring out which reviews are spam or not will solve the problem. “Human beings can’t do it,” he says. “Some people might get it right, some people might get it wrong. I have fake reviews on my webpage and even I can’t tell which are real or not.” You might notice that I’ve only mentioned Yelp reviews thus far, despite the fact that Google reviews — which appear in the business description box on the right side of the Google search results page under “reviews” — is arguably more influential. That’s because Google’s review operations are, frankly, even more mysterious. While businesses I spoke to said Yelp worked with them on identifying spam reviews, none of them had any luck with contacting Google’s team. “You would think Google would say, ‘Something is fucked up here,’” Knapp says. “These are IP addresses from overseas. It really undermines the review platform when things like this are allowed to happen.”