The internet makes it really easy to spread good things and bad things, facts and lies. Don't assume that a post on a friend's wall comes from a reliable source. Don't assume that because it looks like a legit news site, that it isn't embedded marketing, native advertising, or straight-up cult recruitment.
If you've got a soap box, by all means, use it. Be smart, make sure it's sturdy. Don't lose your credibility in a rush to indignation or to catch a bandwagon.
As the saying goes, "Trust but Verify."
Not sure how to double-check your sources? FactCheck.org & NPR both offer refreshers in "Is That True?"
I'm a big fan of Snopes.com and PolitiFact, plus using the Three Source and For/Against rules we learned back in grade school.
Critical thinking, folks. It's important to your sanity and your social media presence.