gsmith - 10:04 am on May 28, 2008 (gmt 0)

It looks to me like the fraud claim rests here (from the same article):

Click fraud can be detected by software that can track suspicious patterns, such as repeated clicks from the same source. Although Citysearch assures its customers that it applies this technology, the experiences of many of its customers shows otherwise, according to the suit. Still, customers are led to believe that Citysearch is in fact actively fighting against click fraud.