I almost always play with everything muted. Nothing worse than cringe voice overs or sex talk that feels completely forced and and not real. I never want to hear the MC or anyone else if its a dude.
It depends on what kind of VA. Games that have proper sound implemented have an extra layer of depth that make them so much better. I don't need every line done, or even any of them, but a bit of good VA for some moans or gasps, or something...it's awesome.
Also don't like voices. Whenever I hear them it sound like one of those popup viruses that says shit like 'YOUR COMPUTER IS INFECTED'. intrusive when your trying to read.