I don't think it's that slippery. There's only a few sites out there that are pure bottom feeders. Valleywag and Dailymail.co.uk are the only two that come to my mind immediately.
I personally avoid anything by Guy Kawasaki because it all just seems like contentless fluff self-promotion, but not sure he is quite Valleywag quality.
... and I wouldn't advocate banning Guy either. It's a personal thing. But it would be nice if I had a blacklist that I could just add his domain to.
but imo, if you do ban them, you'll get a lot of "why ban vallywag and not XYZ"? its a slippery slope.
unless there are already similar sites that are banned. if so, ignore me, i'm a noob.