I think these two sites should not be completely lumped together. Let's let each man talk for himself. From Ken Rockwell's "About" page:
Apparently the world finds my opinions very useful, but remember, they are the opinions of one man. I have a big sense of humor, and do this site to entertain you (and myself), as well as to inform and to educate. I occasionally weave fiction and satire into my stories to keep them interesting. I love a good hoax. Read The Museum of Hoaxes, or see their site. A hoax, like some of the things I do on this website, is done as a goof simply for the heck of it by overactive minds as a practical joke. Even Ansel Adams kidded around when he was just a pup in the 1920s by selling his photos as "Parmelian Prints." I have the energy and sense of humor of a three-year old, so remember, this is a personal website, and never presented as fact. I enjoy making things up for fun, as does The Onion, and I publish them here — even on this page.
Emphasis mine, links to other sites in the original, although I've removed the one that is a promo-code link to a book on Amazon — even found in the about page. (I've got no problem with product linking in general, but the fact that even this section contains one seems... indicative.)
Thom Hogan's site simply says:
Here you'll find extensive information about Nikon photographic equipment and support for all of Thom's Nikon-related books.
And the "about" section is devoted to biography and bibliography. I don't think there ever seems to be a push anywhere on the site for anything but the idea that it's the writings and opinions of one particular expert. Whether it's reliable or not mostly comes down to whether you trust that expertise (and how far you trust it).
It's probably valuable to also include sites like Mike Johnston's The Online Photographer (which has a more journalistic mission, and which is meticulous about distinguishing opinion statements from simple facts and even more so — with a sort of midwestern guilt — about highlighting commercial connections), and Michael Reichmann's Luminous Landscape, which says:
It's easy to be a critic. You just need to have an opinion and a soapbox to spout it from. But when I listen to or read someone's opinions I want to know what combination of knowledge and experience allows them to hold forth on a given topic. Since I pontificate on many subjects in various essay and reviews on this site I figure that you deserve to knew a bit about who I am and what experience I bring to the table in each of these areas.
None of this makes my opinions right. But it means that when I criticize something my opinion comes from some fairly extensive photographic and industry experience.
Am I biased? Yup! I like equipment that produces first-class image quality and that does so with well-designed ergonomics and user interface. A good product needs both. A product fails, in my book, if it only succeeds in one of these two areas.
Do I make mistakes in my reviews? Sure, lots of them. Who doesn't from time to time? I do my best to correct them though when I do.
That seems like the right way to do it — in my subjective opinion.
That's not to say that Ken Rockwell is always wrong. In fact, he's an experienced photographer with a lot of great advice. For example, this article on ultra-wide angle composition is top-notch and extremely helpful. Just make sure to also think for yourself. I'm still not sure if his oft-repeated love of cranked-to-the-max saturation is one of his "hoaxes" — I suspect it is, but there's no accounting for taste. (And, um, even if he's serious, no need to form your own taste around his.)