This is more for printed materials but it can be applied to digital. When I was in high school, our textbooks said Christopher Columbus discovered America and Abraham Lincoln freed the slaves. We now know both statements aren't entirety true. Also, books back then called Pluto a planet which is no longer the case. You see where I'm going?
This was one of the reasons they stopped publishing print encyclopedias. This is the bane of every college student's existence...well one of them. We can't update the content in print material. Publishers simply release a new edition.
Before I invest in any print resources, I look at the copyright date. I'm a little wary of any book published pre-2000's. For me, using a book that old is only acceptable if I'm looking for older info or if that's the only book written on the subject.
There are exceptions. I almost had a heart attack when I saw Bradbury's Zen in the Art of Writing copyright date was 1994. But, it's an amazing book on wiring His advice is timeless.
I also look at the copyright date on a website. (Can be found at the bottom of the page) If it doesn't say 2013, I want nothing to do with it. Some information is timeless, some are not.
As a personal rule, I generally don't use books on the publishing industry, getting published, or being a full-time writer published before 2010. I prefer 2011 but I'll go 2010. The publishing industry changes too often to trust content that old.
This is similar to date. Most websites have content that's updated frequently. Whether it's a blog post, event notice or industry news. For this, I give the site about a week. If the content is a week old, then it may not be the best place to get information. This is on a case by case basis. If they hadn't posted any updates in a week but before then had been posting regularly then, I give them the benefit of the doubt.
No matter your opinion of the government, information found on .gov sites are already vetted. Don't blindly assume everything said is fact but in the world of research, siting .gov is acceptable.
I generally don't buy a book without looking at reader reviews on either Goodreads or Amazon, sometimes both. If you've ever checked out a reader/user review, you know they're as good or better then the critics and there are usually a lot of them. And, they're extensive.
I look at them to determine why people like or don't like this book. 20 people could dislike a book but their reason could be something I like in a book. Or, it could be the opposite. 20 people love the book for something I dislike.
I'm wary of books on Amazon written pre-2010 without a review. One thing this Social Media age has taught us is people like to voice their opinions. If the resource is that old and no one has said anything about it then, it may not be worth your investment. This type of book warrants a library visit.
I use this more for videos and websites. Every so often you may come across a website that looks like this:
It doesn't matter to me if the site is dated 2013, this 90's design does not scream "I know what I'm talking about".
Same with videos. The below video has the potential to be a brilliant resource because of how the content is presented.
What About Wikipedia
You've heard how untrustworthy Wikipedia is. How people have created false content. However, in grad school I read a convincing article about why Wikipedia isn't so terrible. I've come across several instances where someone put content on it that wasn't true and another person, or people, came behind them and fixed it.
This was the argument the article made to why Wikipedia wasn't the bane of every researcher's existence. You have dozens of people working on one entry. Wikipedia shouldn't be your only resource but if you know nothing about a topic, it's a good place to start.
I'm generally wary of any article, blog post or book titled "8 ways to succeed as a writer" or "How to write a bestseller" or "The keys to a brilliant plot." There is no one way to do anything, especially writing. There is no secret to writing; no 12 step plan that'll ensure you write an amazing book. Titles like these are misleading.
You could follow their steps and still produce a bad book. In terms of any writing advice, remember it is their opinion. Even if the content was written by a professional in the field with an impressive resume, it still doesn't mean what worked for them will work for you. No matter the author, I approach all writing advice as suggestions.