After going through their data source, I see some real problems. Untappd users make no distinction between fresh and old beers It’s not my fault that someone decides to hold onto a bottle of Abzug a beer that needs to be drunk fresh and that I haven’t brewed in four years. Of course it tastes like shit. In addition, it appears to be about the environment as much as the beer. Girlfriend just dumped you? I bet that beer doesn’t taste very good.
This make untappd fine for what it is, but not really something that works for their statistical analysis. At least the people who write reviews on Beer Advocate and RateBeer take beer tasting seriously.