I have noticed an increase in invalid activity refunds recently.
I am reluctant to use the words click fraud, mainly because I have no specific details beyond the "Invalid activity" refunds.
I've watched people click on ads more than once as they do research and go back to the search. It's only when I tell them that the advertiser gets charged each time they click do they think about the impact of their clicks. I wouldn't call that click fraud as there is no intent to defraud involved.
I'm also aware of the problem of mobile ads and accidental clicks. That problem was, to some extent, resolved by Google some time back.
What about the bots and networks devised to click, obfuscating their IP?
What about the so called "click farms" best known for generating fake "likes" and twitter followers?
I don't believe we've heard enough success stories in the battle to combat this problem, and it's worrying when I see increases in refunds for invalid activity, which, because of obfuscation, I cannot effectively see why that was invalid.
Have you noticed any emerging patterns of invalid activity?