What's the best way to farm world-drop epic BoEs?

Hi folks, my question is in the title. I see certain people selling numerous vanilla world-drop epics on the AH, which leads me to believe they have a method for farming them. Perhaps there is not a level 70 twink population and thus nobody bothers farming world-drops from TBC?

Is there a higher chance for these items to drop from raid/heroic/dungeon/elite mobs, higher level mobs, or is it just the same (very low) chance across all mobs in that content? If the latter is the case, then perhaps the best strategy would be to find the highest density of easy mobs with quick respawns?

Thanks in advance.

World drops are prolly not implemented correctly (static loot tables) and some of the mobs have actually higher chance of dropping them.

I've only seen rare BoE keep dropping in Hellfire Peninsula, but hardly anything green outside that area. The staff says that some stuff had too much chance that they kept getting pushed off the loot table

I do remember getting an absurd amount of greens and blues leveling through there, and just vendoring all of them b/c they were so common they weren't even worth putting on the AH. I've still yet to see any purples though and I've been watching the AH daily for the last week or so. Would a level 70 req purple even drop in a level 60 zone anyway?

@zerg any idea which mobs have a higher chance to drop them, or is that just a guess?