There are some shady sites out there that peddle totally fake news for ad impressions. I'm fine with disrupting their business model.

But what are the odds that legitimate (or even fringe, semi-legitimate) right-wing news sites bear the brunt of this movement?

There's a long series of experiments on a phenomenon called "the hostile media effect."

Basically if you show two opposing interest groups the same film clip, both will rate it as highly inaccurate and biased against their point of view.

https://en.wikipedia.org/wiki/Hostile_media_effect

I'm excited for the results of Facebook's experiment, but fully expect this to remain an unsolved problem for the foreseeable future.

Yes Facebook did add that feature... last year. Engadget is simply reporting on something Facebook announced they added publicly last year. https://newsroom.fb.com/news/2015/01/news-feed-fyi-showing-f...

Because everyone knows Facebook users are the epitome of fact curation.

Stable door: closed. Horse: bolted.

With great power comes great responsibility.