I did find that the fake article titles were often too "on the nose" to be believable, so I guess that's one level of filtering. But you are right, if you can't explore the article and its sources, you are just guessing whether it is true based on whether it sounds or feels true.

I have another issue with the fact that a headline can be a "real" news headline, from a source that may have a veneer of reputability, but could still very much be full of bias. Is it "fake news" if the article exists and technically contains some verifiable facts, but is otherwise full of propaganda? It gets blurry.