I generally read everything.
Then there's the NPD threads/VGChartz weekly sales threads, where 4 people can go on and have a long discussion, with nobody saying anything of interest. I usually skip those, as I recognize what members are in it, and know that talking to them is a waste of my time.
Then I oftenly enter threads by someone's profile (recent posts), and if they aren't really interesting, I only read Rol's/Noname's/TWRoO's/some other people's posts.
So 3/4 of the time I read it all.
1/8 of the time I skip the people who have quote wars
1/8 of the time I just read Rol's/Noname's/TWRoO's/some other's posts.