I've been building up a relatively large campaign across the PPC engines for a client of ours, and have noticed a disturbing trend with the AdWords vs. Y!SM numbers.

Yahoo! is consistently half the price, and double the ROI. The site's conversion rate with visitors from the Yahoo! ads, which display on Yahoo!, MSN & several smaller engines are consistently outperforming the Google ads by a magnitude of double or better. These are the same ads, with the same landing pages and the same search terms. The cause is a mystery indeed, and I don't want to chalk it up entirely to demographics (yet).

I will say that Yahoo!'s performance has been exceptionally good - the conversion rate across the terms is over 10%, while Google's is under 5%. CTR is also exceptional - 7.5%, while Google's hovers around 4.5%. I'm testing new ads and further refining the landing pages, but I'm skeptical about what Google is reporting and certainly very concerned about just how "inflated" their click and impression count is. Rumors of widespread, low-level click fraud are nothing short of alarming.