You need to. Pretty much any thread you lot get involved with turns to shit. And you are very much part of the common denominator.
As you say, he's not the only one guilty of derailing threads, but it IS a fact that whenever you refresh the board and see dave's name last posted under a thread: a) it's always the same tiresome subject and b) the thread has turned to shit in part because of him.
To be honest, if it was my board, I'd have banned dave a long time ago. He adds absolutely nothing to the board, except to get on people's tits.