What do I mean by skimming? Clicks that should be counted towards you are not! on the reverse side of it... If you are paying for 10 clicks and two are invalid and you are not refunded those two other clicks.
I could not answer that. The only people that would really know if the CPC companies themselves that do it, that's if they do, but I personally wouldn't think they would as it's just going to cause more damage than good to their company if it got out into the public on what they were doing.
