I think that's setting the bar a little too high. What's reasonable to expect, IMO, is proper fact checking (which was your other, completely valid, point) and a level of background knowledge (including carefully kept records) that allows the blogger to analyse and put into context. A good blog post tells me when an offer is best in class, for example, or when to expect a fare sale based on previous years. A poor one regurgitates press releases, marketing blurb and other blogs.
Still on wrong/misleading, VFTW let some more hurriedly written nonsense slip through into a post last week: "Even most Asia Pacific carriers have eliminated first class."
Reduced, certainly, in many cases, but
eliminated?!
In regards to expert information, I think that bloggers with a relationship with Chase could certainly pass along
accurate information about when Chase offers they're pushing might end. The bloggers didn't even do that, tossing out useless speculation instead of saying, "Chase hasn't yet given me information about when this offer might end." The rest of the expertise I expect can be gained through the kinds of fact checking and analysis you mentioned.
I don't expect bloggers to be right all of the time, and there can be legitimate differences of opinion, even amongst experts, about the best way to do anything, whether it be collecting points or performing brain surgery, but some bloggers do themselves no favors by consistently offering no added value in their posts.