One interesting takeaway:
"Last week, acting on a tip, we logged into Facebook’s automated ad system to see if “Jew hater” was really an ad category. We found it, but discovered that the category — with only 2,274 people in it — was too small for Facebook to allow us to buy an ad pegged only to Jew haters.
Facebook’s automated system suggested “Second Amendment” as an additional category that would boost our audience size to 119,000 people, presumably because its system had correlated gun enthusiasts with anti-Semites."
Interesting correlation. This is based on data mined from a gigantic sample size. If the system says there's a correlation it's because there is, not because it's inferred by a person. Make whatever conclusions you want to make. None are good.