Good journalistic practices:
0) Don't make things up
1) Ensuring at least two sources for claims
2) Ensuring one of your sources isn't using your other source as a source, because that would just be one source.
3) Employing proper validation of the sources identities as employees of firms in a place to know what they are saying
4) Being very careful to separate what you heard, what you inferred, and what you speculate
5) Being very careful to understand what your sources know, what they infer, and what they speculate
6) Not falling for the tendency of low-ranking sources to represent themselves as more central, connected, or knowledgeable than they are.
7) Not using the fact that other journalists are reporting things as additional coroborration without being sure that their sources are not your sources
8) Being clear when you're repeating a claim another journalist made and when you have independent confirmation about a claim another journalist made
9) Reporting honestly without baiting, teasing, hyping, or withholding
10) Not trying to claim plaudits when you're right if you don't take lumps when you're wrong--"take this with a grain of salt" is absolutely not professional in any capacity, because if you turn out right, you're not going to say "No, no, I was wrong, I didn't know it".
11) Not taking excessive credit for reporting something that a reasonably informed speculator with no information would have concluded.
LPVG are very clearly not making up everything they write whole cloth! It's also quite obvious that as a former Destructoid writer and enterprising blogger-journalist, LKD is capable of seeking out sources--some of which she had probably cultivated before all this. And I take her at her word that her "master list of claims she's made" actually do have the sources she claims they do, and further that she's smart enough not to fall for a faker.
Where I think they are hurt is participating in the circular group of Twitter/YouTube/blog leaker-speculators, who frequently violate 4, 5, 6, 7, 8, and especially 9, 10, and 11.
For example, if you have a source in Bethesda Germany who tells you cuts are being made to the new Wolfenstein for the country, that's very plausible. But you might want to verify that they know this for a fact, instead of assuming it to be the case because everyone knows Germany's laws require cuts to Nazi-related content. And then you might further verify that the person's claim is specific to Germany. And if your source also tells you that Elder Scrolls VI is not being worked on, but the source is a QA tester in Bethesda Germany on Wolfenstein, then maybe they aren't in a position to know that Elder Scrolls VI is being worked on or not, and they are making an inference based on what they've seen and heard that is not true. And if you report it as "SOURCE: New Wolfenstein Being Censored", you need to be mindful that what your source was telling you was probably only true for Germany, if at all. And you don't get to weasel out of it by saying "Take with a grain of salt"--and anyway, in the end, if you're right, you've just told people the most obvious thing that anyone could have guessed even without knowing anything.
The good thing about LPVG is that although some of their claims are the normal wishy-washy Nostradamus bullshit, they've made specific claims about specific games and specific claims about those games being prepped for this presentation. There's an obvious W and an obvious L that we can take away tonight. That kind of transparency is good, and I think JSchreier was getting at that.
Oh, and one final thing--someone being correct in the past may well mean that they are not totally full of shit and making up things whole cloth because their psychic premonition told them that Zelda: Valley of the Flood is M rated and b-b-b-based, but it doesn't mean that they are exercising discretion and good practices going forward. The opposite is definitely true--if someone goes out on limb and says StarTropics III by Retro Studios is going to blow your socks off and they announce Donkey Kong, you write them off forever. That's not a "things change", that's a "full of shit". But someone being right does not establish that they will continue to be, and that's why constant vigilance, skepticism, and holding people accountable for errors rather than just remembering successes matters.