Dissuade Conservatives from Using Dishonest\Extremist Sources
Unfortunately, no matter how non-credible a right-wing source is, it's properly sporting to refute their actual argument first if you chose to engage. If someone shared some nonsense by Brietbart or Getaway Pundit for example, this is an opportunity to educate everyone involved in the discussion on the truth.
If the shared article mostly just misinforms and doesn't also peddle extremism, the tactic we like to employ in this scenario is to always assume the poster is a good person who has merely been duped to always believe an incredible source (Sharer = good, Shared Source = Bad).
So, respond with an informative, factual rebuttal on the issue debated and then proceed to explain how the source isn't to be trusted.
This is one of the few cases where we encourage you to reply directly to the person rather than educate a broader audience. The goal is to get conservatives to disavow the source but not their idea to be taken seriously. Get them to realize they should stop linking to these crazy websites. Explain to them nicely how the source cannot be trusted.