I've definitely done a lot of research on this genre since I heard Dimmu Borgir and discovered that people actually hate them...not because they're not satanic enough, or because their studio albums are high quality.
See, originally, black metal was not an underground Norwegian corpse-paint fad. Back in the late 70s and early 80s, when Iron Maiden was making metal pop(ular) and the hair-metal-genre was spawning because of it, a band arose in Britian to defy the popular metal and to be faster, louder and darker than anything else: rather than deny accusations of devil-worship, this band would embrace it! That band was Venom, founder of thrash and death and one of the four founders of black metal!
Shortly thereafter, another such band arose out of Denmark: Mercyful Fate. This band even stylized the punk-rock habit of using black-and-white make-up to appear deathly (at least King Diamond did). On the very heels of the release of Melissa came from out of nordic Sweden Bathory, with its self-titled "Pentagramaton/goat-head" album. Though thrash in nature, Bathory was satanic in lyrics, Quorthon's voice neither howled like Cronos or wailed like King Diamond, but growled, and every album had crappy studio quality. Hellhammer also came forth (albeit somewhat earlier), releasing EPs similar to what the other three had begun.
In the 90s, with Bathory creating viking metal, Hellhammer becoming Celtic Frost and King Diamond with his solo-career, a new age of black metal emerged from the frozen fjords of Norway. Taking almost every trait brought down from the four-forefathers (corpse-paint from Mercyful Fate and punk rock bands, speed from Venom, poor quality and shrieking vocals from Bathory, black-n-white album sleeves from Black Metal, Nuns Have No Fun, Bathory and Death Fiend and the general satanic-ness from all of them), bands like Burzum, Mayhem, Gorgoroth, Emperor, Satyricon, Enslaved, Immortal, Goatwhore and Dimmu Borgir (some of these might not be from Norway, idk) brought the genre into what it is today with their refusal of public exposure (except for DB), and their criminal/grotesque antics (Aarseth selling Ohlin's skull, Varg burning churches and killing Aarseth and Gaahl's assault charge and all the others I haven't heard of or forgot to mention).
Now any band who sings dark, "satanic" lyrics but does not conform to the underground-corpse-paint-poor-quality-n-arsony trend of the Norwegian corpse-paint acts isn't really black metal. That is true, for Dimmu Borgir hasn't burned any churches (the Bible Silenoz threw towards the toilet didn't even land in it), nor are they underground, nor do their albums have poor quality. Cradle Of Filth has the asthetics and trappings of black metal (they even sang songs that were that brutal and extreme in their early years), but to call them black metal is tantamount to insulting Iron Maiden, Dio and Slayer among a group of "heavy" metal fans. These days, most Norwegian acts don't even have guitar solos!
Oh, what I would give for someone to bring back old-school, Venom-esque black metal!