If you make incredibly good or incredibly bad advertising, on any medium or channel, increasingly a measure of effectiveness, or ineffectiveness, beyond pure sales and calls to the corporate complaint line is quite simply people talking about it in measurable and trackable conversations online. The Air Force even has a flow chart for how to respond:
Recently I was part of a broadcast campaign that garnered a couple million views on YouTube without any action on our part apart from a TV buy. The YouTube views led to a few thousand comments, 99% of which were positive from the brand's perspective. However that 1% negative primarily came the first week. The trolls sure are quick. Our client stood fast, we were very proud of their resolve, they directly contacted the upset to explain the strategy/concept quickly mitigating their concern. It went on to be one of the most successful campaigns in 20 years for the brand.
How a brand responds, when they achieve their goal of "breaking through the clutter" or whatever terminology your particular agency happens to use, is really bringing judgment back into decision making. It is also a further example of the fact that in today's world all media is social, not just "social
Of course the fact there are conversations online isn't new. I can only comment on my work but we've been tracking these things since early this decade and using forums and closed communities to disseminate content since early this decade. My elders were doing it long before that using dial up and little cradle things with binary code and handsets. What seems in the past 52 weeks to have materially evolved is it has grown out of the echo chamber into a more mass societal level. One might say it has hit the Wal Mart crowd or simple achieved a degree of critical mass. Or whatever aphorism you prefer.
What fascinates me in the dialogue around creative down in the comments is most people assume the agency and client didn't already consider the obvious "problems" and "flaws" that immediately come to mind to a well intending citizen. This probably says something about the public perception of marketers, well, at least the bankers are making us look honest these days...