Welcome to WebmasterWorld Guest from 18.104.22.168
Forum Moderators: open
This is, IMO, a good thing (as long as other options to deal with defaults are made available).
In my limited testing of YPN (Yahoo Publisher Network) I have noticed that the ads default to commercial ads of very generic variety (i.e. ISP offers, loans, online degrees) when the page has not yet been spidered.