A Cre8asite Forums member notes that instead of getting targeted Google ads, he is seeing a more pervasive theme of ads for Google AdWords:
It used to be that those pages had some sort of general ads on them, often four different text ads (in a banner). Most often they were fairly well targeted to the general site theme. However, since about a week or so I am really seeing a push of "full width" ads for Google Adwords.
He speculates that this may have something to do with him cutting down on his own AdWords campaign:
About a week ago I killed a lot of my Adwords campaigns (moving them to separate accounts), my normal Google account is now spending about 5% of the Adwords-costs that I used to have.
Are these personalized ads based on recent user behavior?
The user speculates that Google is advertising its own services and may therefore be bumping out other higher paying customers. Is this possible? He thinks that it is and that Google is paying for it themselves.
But by bumping off higher-paying ads they're actually paying for the space (opportunity cost). By grabbing a whole wide Adsense block instead of allowing 4 "paid" advertisements they're losing the money which a potential click would bring. It's not cheap.
An AdWords advertiser also notices that his click-through-rates are lesser than expected.
Well, something is definitely up with AdSense: for the past 4-6 weeks, my CTR has been a paltry 0.5%, with 0.1% routinely popping up. Pathetic waste of space.
My typical CTR used to be around 1.5-3%, depending on the day. Not bad for a site aimed at webmasters!
But not everyone is seeing any difference in behavior.
If you are noticing anything, add your $0.02 to the discussion at Cre8asite Forums.