Are airbnb Guest Reviews Too Good to be True?

Higher than the average rating? 95% of Airbnb listings rated 4.5 to 5 stars

From Mashable, February 25, 2015

Is every available listing on Airbnb above average? Before debating the mathematical improbability, consider the evidence: Almost 95% of properties listed on the site have an average user-generated rating of either 4.5 or 5 stars, where 5 stars is the maximum rating available. … By contrast, properties on TripAdvisor had an average rating of 3.8 stars, according to the researchers.