There's zero evidence that this exists, if only because there's very few examples of working microtransactions systems at all. Adverts are
not micro transactions. (I don't care how you want to use that word - nobody else uses it like that)
But, all of the systems that I've seen (Blendle, video games) have had no problem at all with fraud, and a very small amount of annoyance to value delivered.
There's simply no reason to believe that this will be a problem, either empirically or theoretically.
