fordo23 - 3:59 am on Oct 15, 2007 (gmt 0)

This conversation is also running on this thread [webmasterworld.com ].

I have done some thorough investigation recently as I had terms increase in impression share by 300% overnight. The result was identifying new sites into the Yahoo 'search network' partner sites. The new domain blocking feature can't come fast enough for me!
Yahoo search spam accounted for 8% of our clicks last month, and of course conversion rates so low it tips those whole adgroups beyond profitable. As a result I turned off the offending keywords & adgroups till the option to opt out becomes available (these are mainly big generic terms for our industry). Since turning off these adgroups our spend has dropped dramatically but obliviously CPA has improved nicely. I’m expecting to also see decreased clicks from the Yahoo search partner sites as a result. I've had recent discussions with other search marketers (different industries to mine) who've now done investigations into their referring domains etc, and have come back reporting similar offences. They agreed it's seems to have increased dramatically in the last 2-3 months.