The source of good healthy water is a criterion for having good healthy water in your glass. The water provenance is marked and branded.
How to prevent fake branding? Watermarking and other authenticity detection.
-secure identification of source
-secure transmission channel
Ensuring data has not been modified.
Even good journalists can sometimes be fooled by fake news, but more often than not, they will check and check again the authenticity of the source and the unadulterated content it shares.
There can always be systemic errors.
The Catholic church has long prevented the information that the earth was rotating around the sun to reach the believers.
That's a reinforced by design systemic distortion.
We know distorted sources. The problem is not that they can't be trusted fully, but when they nevertheless say something true, and we won't believe them where we should...
In Information Theory we have Channel (authentic) and noise (scrambling, injecting erroneous data). This can be seen through game theory with adversarial games. The adversary occasionally distorts the truth. Totalitarian regimes do. Does it mean that a regime occasionally distorting the truth is necessarily totalitarian? No, but it may become one, with people being disoriented by this noise injection in the information channel.
Let us not forget that the transition from non totalitarian to totalitarian is easier than the reverse, as history has shown.
I think the best way to identify fake knowledge is to use your own judgment. Be it worldwide web or printed media- what is fact and what is not cannot be found from any source. You can use your own judgment, talk to people about it. If its technical refer standard books.
To identify the authenticity of the publisher:
Make a note of website, duration of being in field, publication source, contact address and other such information.
If there are any lists or authenticated source manual- please let me know.