here's another one

Orochimaru sends someone to kill the Uchiha clan, but Itachi kills him just after the enemy killed everybody but Sasuke. So he takes responsability on the killing to prevent Sasuke from getting himself killed. and then he joins up with akatsuki to find the true killer.
by that time, Kabuto sneaks into whatever group who came to check out the killing, and see's the killers' body and hides it from everybody else, without infiorming Orochimaru.

so this way, Orochimaru thinks that Itachi killed the entire clan before his man got to it, and so he speaks nothing about it once Itachi joins the Akatsuki, but Itachi doesn't know who sent the attacker, or believes that the attacker acted on his own, so he doesn't suspect Orochimaru and tells Sasuke to keep on living, so he could build the Uchiha clan once again...

so you see, this way, everybody's fucked up with only half-truthes and we, the readers, win a nice plot...