While click fraud is an ongoing problem with PPC, Jennifer Slegg stumbled upon an example of one site owner's misguided attempt at combating it.
A Canadian moving company
chose to use an automated service to detect (and deter) fraudulent clicks, but the system was unable to differentiate between real customers and bots or scammers. Visitors that had arrived by clicking
on a specific AdWords ad were redirected to a custom landing page -- one that accused them of click fraud and threatened legal action.
The error has since been corrected, but Slegg's in-depth post details the myriad ways that the site owner had lost out, from the valid leads that likely went to a competitor, to the fact that the clicks had already been paid for.