Some jazz blogs are straight ahead educational: "Download transcribed solos by Brownie, K.D. Miles, etc." God bless these people.
Most jazz blogs do the work of 'exposing' the music-"The Fearless Fosdyke Four will be at the Bluze and Brew Tavern/Festival/Restaurant this weekend. Don't miss it." Or: "You'll want to check out the FFF's latest CD release on the Gasoid label, available at Amazon/ Walmart/CD Baby/iTunes..." It works better if they post audio or video of the group in question.
Similar blogs, but with more critique, give you a blow by blow of concerts or cd's. These are almost always self-selecting for material the reviewer likes, so seldom is heard a discouraging word. This is often the home of The Top Ten List (see my other post on this menace).
Then, there are interview-oriented sites: "When last heard of, 33 years ago, Desmond LaBrea was on the road with the Jules Verne Aquanauts. We discovered him making baignets in Paduka and asked him why he left the world of riffing for the world of sifting..."
In the blogs above, there is often room for exploring jazz esoterica, i.e.: How many jazz groups have been named after lesser tributaries of the Snake River? I love that stuff.
Then, there are jazz blogs that are more 'meta.' They ask questions and may suggest solutions: "What's up with jazz? Where is the audience? Where's the money going?" "Let's do a Jazz IPO." It is in this arena that the rough-and-tumble lurking in the hearts of jazz people sometimes breaks out. I find the level of emotional engagement here seductive and enjoy this arena. This is where we get closest to experiencing personal agendas, but mostly, the emotion remains subtext, and infuses formal discussions on the redistribution of money, etc...
I have had a long musical life, marked with some pleasure, some pain and, at this point, a feeling of having read the same newspaper headlines over and over. I think this experience helps me sniff out magical thinking. Others see me as cynic. Both views are correct. We're all subject to the vagaries of age, temperament, career success, sex life-It's the human thing and, to the extent that the jazz blog world reflects this ungodly mess, I say it is better for it.
Some say the old battle between the Beboppers and the Moldy Figs was bad for jazz. Don't know. I think it was a reflection of the emotional importance that the music once had in many people's lives. Most homicide victims fall to the hand of someone they love, or once loved. By the same token, you're probably more likely to jump into swirling currents for the adored one. I'm not sure how many jazz bloggers I'd take the plunge for, but that's another story.