Actually, thinking of that, I am yet to see the ANBU being useful in anything else than getting killed finding corpses, and watching.
Starting by the three of them who died, just like that, in Sasuke hospital room.
The Sand was summoning a giant snake in a giant circle and they didn't notice it. As a matter of fact, one of them noticed a sound ninja but didn't bother to stop and check.
And those three watching the 3rd's fight were pathetic. The two Kazekage guards that one of them kills, were actually those four sounds henged who not only not died, but did a good job protecting Oro.
I think the Anbu sucks even more than the chunnins.