We’ve found that the buzz is true; turning off Google’s Search Network and running your campaign on Google search alone is the best way to go. A lot of the Search Network traffic (we’re not talking about Content Network, but Google’s affiliate search partners) doesn’t carry much value because a large majority of it comes from parked domains with a generic search box, spam directories and portals, and other low-content sites. Some accounts we’ve nearly run into the ground sharply avoid hitting the runway after we turn off Search Network, and then perform exceptionally well. It’s just one more tool in your PPC management arsenal, so don’t forget about it!
Google’s products are great, and we’re sure that they will eventually figure out a way to phase this horrible waste of marketing dollars that’s currently called Search Network out of the picture. But there’s no sense in you helping them (in an expensive and ineffective way) through the tranisition. If you can’t find enough traffic on Google search alone, then by all means set up separate campaigns with slightly less relevant keywords or on the Content Network, with a different bidding and ad strategy, but don’t use Search Network until they clean it up first.