Accusations of click fraud are nothing new in affiliate marketing, but the volume of complaints about Facebook recently has raised more than a few eyebrows. Now even the social networking gorilla is acknowledging “suspicious” activity. Facebook aims to nearly double its revenue this year to about $550 million, including a big boost from CPC ad sales.

As Michael Arrington points out on TechCrunch, scores of outraged affiliates have been venting their rage on WickedFire (forum membership required), claiming the number of clicks reported by Facebook is much higher than the number showing up through tracking tools like Prosper202/Tracking202.  “Tracking 202 is telling me 11 clicks…Facebook is telling me 145,” notes one affiliate. Another writes, “There are lots of places to buy traffic, some that will even actually give you the traffic you are paying for. Facebook is never going to admit to what’s going on. I can almost guarantee you that.”

The network is asking affiliates to provide documentation of any problems they’ve observed. A Facebook spokesman says, “Over the past few days, we have seen an increase in suspicious clicks. We have identified a solution which we have already begun to implement and expect will be completely rolled out by the end of today. In addition, we are identifying impacted accounts and will ensure that advertisers are credited appropriately.” Stay tuned!