They used to do the whole traditional garb thing, which pretty much seems to be the most generic defining factor of angura..
but it's not. there are angura bands that don't necessarily dress in kimono or military outfits. angura is similar to eroguro, but eroguro is a pre-WWII movement, angura is post-war. so they seem to me as little different in their attitute. angura has a lot of 60's intervention spirit, revivalism and at the same time an attempt to innovate. eroguro seems to have more of a... zest for life? indulgence and depravity just for the sake of depravity? (not unlike its contemporary movements in the west...) how can you see the difference if not for the themes or the attitude of the bands? that's where the hanging out with certain groups matters, i think; i could agree if you said that maybe there are angura bands that aren't true to the angura spirit and become angura just for playing at the same lives as other angura bands and so on.
i checked the wiki articles and none said onmyouza were angura, and i'm pretty sure that nothing of the kind is on jrocksaga either
so where are people saying that onmyouza are angura? inugami on the other hand, they call themselves angura. which makes it pretty easy to say for sure, yes they are angura. (of course it helps that they have weird lyrics, visuals and general outlook on life.)
angura is not like visual kei. and if angura was just about image, then picture mushy-ballad gackt dressed like guruguru eigakan... would gackt be angura then?
(oh my.... so tempted to "photochop" this!!! )
on a different note, i've tried looking for books on angura only, specifically on music, but found squat. not even japanese authors... though my very-very limited japanese wouldn't be of any help if i did come across any such books
there is however a new book on terayama shuji being released soon if anyone is interested. (link)
i think understanding angura theater/cinema/literature helps to get a better grasp on what angura aims for. btw, there's a sentence on that book's synopsis that feels very appropriate (and probably sums it up better than i ever could):
"Among the key themes she explores are the ruins of personal and national identity in the wake of Hiroshima, the Occupation, and the anti-American demonstrations of the 1960s; the paradoxical links between Japanese nostalgia, performance, and postmodernity"
... okie, i'm going to try and post this before my computer collapses for good, the poor thing (in any case, i've said pretty much all i had to say on the matter