londrum - 7:53 pm on Sep 15, 2011 (gmt 0)
i think the way that google looks at interest-based ads is this...
they have a load of advertisers that spend a lot of money to get their ads on our sites. and they have even more advertisers who spend very little, so they cant compete.
so what google needs to do is increase the number of sites on which their ads can appear. because then they can burn through the small advertisers budget quicker.
before interest-based ads began, their ads might have been competing to appear on a thousand sites, but now they can compete to appear on hundreds of thousands.
so it doesn't matter if individual publishers are seeing their CTR drop, because overall google is bound to see their own go up