Blood Presence

Ok, I'm not here to bash DKs or anything of the such, but i've been tanking while lvling my way to 85, and it seems that probably 75-80% of the time i join an instance with a dk in the group, they are dpsing in blood presence. correct me if im wrong but isn't blood pres the dk tanking presence for increased threat. Im not sure if it is viable to dps in blood pres, but it definitely makes things harder for me to keep aggro on as well as the healer to keep 2 people up instead of just one. I always tell them to switch to a diff presence but they either dont reply and continue on or some will occasionally switch.

I realize that at my lvl a lot of dks are fresh out of the box. so i understand that they are still figuring out their class, or dont have enough gold to get dual talents and have blood as their main spec. but am i in the wrong to tell them to switch presence, i feel like im being an ass telling them how to play, eventhough my only intent is to give them some constructive help.
even if he is dpsing on blood spec (totally wrong too), he should use unholy presence
as a DK you NEVER dps in blood presence!

Blood presence used to be a DPS presence before it got swapped with Frost Presence in 4.0. Some people don't read tooltips/forums/anything, and are oblivious to changes. Ask them to switch, and boot them if they don't.
maybe they were just solo questing and forgot to switch it over, i know i've done that... but after the first trash pull, you should be able to notice that you're pulling off the tank.
Two months ago, every single PvE death knight was expected to DPS in Blood Presence. Some of them may not have realized that things got switched around. I would give them a quick reminder, I think most of them would appreciate it.