Then just put it on mute. I've never seen people even say much that is useful on vent aside from explanations. Usually it's just "run" or "watch out for the fire". None of which is all that surprising, I mean this stuff is scripted. So I just put it on mute and listen to music. My guild also knows this, so they just message me to un-mute when they need to have a chat with me. The main tank in our guild does the same thing actually.

Vent truly is optional in most cases. Before my subscription ran out, I did a full clear of Naxx25 (a pug no less!) with the "main" vent muted while being on a second vent with a couple friends who were in the same run just shooting the !@#$ through the entire thing. I did try to explain the positioning for melee on KT (since most of them including the RL and MT had never done it on heroic) but I was basically completely ignored. We 1-shot him anyways.

When I resub and start up a guild it's definitely going to be vent-optional.

Vent allows for multiple channels... My guild has a specific channel for dungeons/raids. Granted there's random chatter in that channel during dungeons/raids, but that's only during downtime when mana and health is being replinished...