They share the viral content on their Facebook pages, which spreads from there, and people like their Facebook pages. The most spammy ones use clickjacking; ba

They share the viral content on their Facebook pages, which spreads from there, and people like their Facebook pages. The most spammy ones use clickjacking; basically they throw up something that covers the page with an ad (or a "like us on facebook" prompt), and use some JS to turn a click anywhere on the site into a facebook like. That's playing with fire though, as most of those pages get flagged and shut down. They do get a little bit of traffic from Google because their social reach is extreme (one of the bigger things Google looks for now) but it's around 85% pure Facebook traffic