Airbnb’s now-defunct “Airbnb Plus” certification program didn’t just help the listings it approved: It also unintentionally hurt many hosts who were left out, according to a new study from the Cornell SC Johnson College of Business.

Airbnb Plus launched in Los Angeles in 2018 to reassure travelers by certifying a small number of listings that met strict design, cleanliness and amenity standards through in-person inspections.

Heeyon Kim, assistant professor in the Cornell Peter and Stephanie Nolan School of Hotel Administration, and co-authors show that certification made noncertified homes seem riskier by comparison, potentially pushing some travelers to book hotels or choose other alternatives.

“Certification programs are usually designed to build trust. On digital platforms like Airbnb, where guests can’t physically inspect what they’re buying, trust matters,” said Kim, an author of “When Certification Backfires: Negative Spillovers on Noncertified Offerings in Airbnb Plus,” published April 27 in Organization Science. “We found that Airbnb Plus homes were labeled “verified” and marketed as more predictable and hotel-like. In theory, this should help everyone: Guests feel safer on the platform, certified hosts earn more, and uncertified hosts benefit from the platform’s improved reputation, but our research suggests otherwise.”

Co-authors include doctoral student Qian Wang, M.S. ’21, and Martina Montauti, assistant professor at the University of St. Gallen.

The research team compared Los Angeles, which had Airbnb Plus starting in February 2018, with San Diego, which did not receive the program until that fall. Because the two cities are close, operate under the same regulations and share similar tourism patterns, the comparison allows the team to isolate the effect of certification itself.

Using detailed booking and revenue data, the study found that after Airbnb Plus launched, noncertified listings in Los Angeles made less money than they would have otherwise. The scale makes this striking: Airbnb Plus listings made up just over 3% of the Los Angeles supply.

“By explicitly labeling some homes as ‘verified,’ Airbnb unintentionally made the lack of verification stand out more sharply for everyone else,” Kim said. “Guests scrolling through search results saw certified and uncertified listings side by side. That contrast made uncertified homes feel more uncertain or risky, even if their actual quality was just as good as before. In simple terms, certification didn’t just say ‘these homes are great.’ It also implied, ‘the others are unknown.’”

When faced with that uncertainty, some guests didn’t downgrade to a cheaper Airbnb. They exited the platform entirely, an option that’s easy in cities like Los Angeles with abundant alternatives.

The negative effects weren’t uniform. The study finds that some noncertified hosts were protected from the downturn. Listings with high ratings or lots of guest feedback suffered less. Reviews acted as an alternative signal of quality, countering the missing Plus badge.

Less direct competition also mattered. Homes that weren’t directly comparable to Plus listings because of their price range were less affected. Listings that were harder to replace with hotels or other off-platform options saw smaller losses, because guests had fewer alternatives. These patterns support the idea that the harm came from perceived uncertainty. Where uncertainty was reduced, the damage faded.

Airbnb officially ended the Plus program in 2023, after quietly scaling it back years earlier. While certified homes received higher prices and visibility, the program required inspections, fees and ongoing compliance, making it difficult to scale.

“Our study suggests a deeper problem: platform-wide costs. Airbnb doesn’t just manage a handful of premium hosts; it governs millions of everyday ones,” Kim said. “If a certification program harms most participants while helping a small subset, it risks alienating the base that powers the marketplace.

“For policymakers and researchers,” Kim said, “our study highlights the need to examine certification’s full distributional effects, not just headline benefits.”

Sarah Magnus-Sharpe is a staff writer for the Cornell SC College of Business.