Even well-educated people often have trouble judging the quality of news outlets. Here’s a simple but very effective tip: look for paragraphs like this one, from an recent article in the Washington Post:
This account of how McConnell and enough Senate Republicans blocked witnesses from entering Trump’s trial — the issue that was most in question during the contentious proceedings — is based on interviews with 13 senators and other officials familiar with the deliberations who spoke on the condition of anonymity to talk frankly.
You just won’t see careful, accountable sourcing like this in unreliable or outright fake news sources. Instead, you’ll find heavily biased sources mixed with unsourced assertions.
But what if the Post just made up those sources it claims it has? No mainstream news source does that, and the claim that they do is simply a lie, told by people who benefit from undermining trust in the facts.
To be a mainstream news outlet is to follow the rules of news reporting. Those rules are well understood, carefully guarded, and strictly enforced when they’re broken. On the rare occasions when a mainstream reporter actually has invented sources, that reporter has been fired and the outlet has published prominent corrections. For example, see the case of former New York Times reporter Jayson Blair from 2003.
Mainstream news outlets follow the rules of reporting partly because their staff actually believe in those rules and that’s why they became journalists, more pragmatically because those staff members are in the profession of uncovering and publicizing wrongdoing and so are the worst kind of people to try to enlist in a coverup, and even more pragmatically because the mainstream outlets’ business model depends on it: their advertisers want to reach a large audience of the kind of people who want reliable news, and corporations, investors, and others who are making critical decisions need reliable news on which to base those decisions. Unreliable news would cost them a lot, and so they would get their news from some other outlet they could trust.
Unreliable news outlets make their money by selling sensation; reliable ones make their money by selling accurate information. Apart from the real ethical considerations involved for mainstream outlets in following the rules, it would just be stupid for them to do anything else.