Head to your local library and hit the archives. From yellow journalism to papers owned by political parties, bias and dishonesty has always been a problem.
Of course, data scientists have their political opinions as well. As do journalists deciding which data to publicize.
https://m.youtube.com/watch?v=qV3gO3zxQ1g
The period probably began with Lippmann's Public Opinion, though it was coverage of the Second World War that probably marked the start of the true peak. By 1980, something was already decidedly off.
I'm reading Robert McChesney who does a very good job of recapping the history in Communication Revolution.
Could we trust them or did we simply not have the means to fact check them and communicate the errors? Awful current affairs programs were around before the web and they were reporting some pretty dubious "facts" back then. Tabloids have been around for 100 years, maybe more.
Because of that, media was regulated differently. A more diverse body of media (pre-media for profit news and consolidation) as well as the fairness doctrine and a non-profit public service expectation were all strong norms and law in play.
Technical limits forced all of us, including the media, to take it more seriously.
Yes, we could trust them more than we could now, but also yes, we could not check so easily too.
Choosing what is important to include or what not to include is dangerous.
Once upon a Time you could mostly trust the news but these days we have "no spin zones" which are in fact entirely spin. You can no longer sit back and consume news, to get the real facts requires a great deal of effort and attention which is exhausting.