I ran a list of test cases through bs-detector, and the results were disappointing.
It correctly identified these sites:
http://naturalnews.com/ JUNK SCIENCE
http://endingthefed.com/ EXTREME BIAS
http://realnewsrightnow.com/ FAKE NEWS
https://conservativedailypost.com/ FAKE NEWS
http://nationalreport.net/ FAKE NEWS
http://prntly.com/ FAKE NEWS
http://beforeitsnews.com/ FAKE NEWS
http://www.prisonplanet.com/ CONSPIRACY THEORY
http://www.infowars.com/ CONSPIRACY THEORY
https://www.rt.com/ STATE NEWS SOURCE
But it missed some others:
http://krbcnews.com/ -- not flagged. (this leftist fake news site is impersonating the real KRBC-TV!)
http://therightists.com/ -- not flagged.
http://drrichswier.com/ -- not flagged.
http://usamagazinestudio.com/ -- not flagged.
http://reagancoalition.com/ -- not flagged.
http://principia-scientific.org/ -- not flagged.
https://moneymorning.com/ -- not flagged.
Worse, the list also shows strong leftist bias. It wrongly flagged five excellent, trusthworthy conservative sites, four of them for supposed "extreme bias":
http://www.drudgereport.com/ EXTREME BIAS
https://ijr.com/ EXTREME BIAS
http://lifenews.com/ EXTREME BIAS
http://www.dailywire.com/ EXTREME BIAS
But NONE of the far-left sites I checked were flagged. For instance, although the highly respected anti-abortion site LifeNews.com was flagged, I checked about two dozen pro-abortion sites, and none of them were flagged.
A lot of sites are marginal/dubious. Left-wing dubious/marginal sites are never flagged, but dubious/marginal right-wing sites are often flagged:
** These five dubious left-wing sources were not flagged:
https://mediamatters.org/ -- not flagged.
https://www.splcenter.org/ -- not flagged.
http://www.rightwingwatch.org/ -- not flagged.
http://www.hotwhopper.com/ -- not flagged.
https://www.buzzfeed.com/ -- not flagged.
** Three of these five dubious right-wing sources were flagged:
http://www.wnd.com/ EXTREME BIAS
https://www.newsmax.com/ -- is very similar to WND, yet not flagged.
https://www.thenewamerican.com/ (the Bircher site) -- is the least reliable of the four, yet it wasn't flagged.