WotLK How to drop reputation?

[Flereous]

How to drop "Steamwheedle Cartel" reputation on Icecrown?
I've tried killing guards (from exalted/revered, with checked "At War") in all 4 camps - Booty Bay, Gadgetzan, Everlook and Ratchet, but not losing any reputation with any of them. The only thing I've managed to drop was Booty Bay from exalted to 20xxx/21k Revered by killing few regular npcs, but once Revered I've stopped losing rep doing that.
Is there something I'm missing, or the way it should be done is just broken now?

[Flereous]

Anyone? Any help will be appreciated..currently doing "Insane in the Membrane", but I want to do Bloodsail Admiral before finalizing the involved reps.