LavingRunatic - 7:32 pm on Jul 21, 2012 (gmt 0)
I've tried paid discovery a few times and not had any success. No ad clicks. No facebook shares. Now, maybe my content is poor, but I don't think so.
As aristotle mentioned, the site does visit yours in an iframe. However, when I look at my GA, I see Stumbleupon as a referrer so yes, Google does see it. I don't think it matters, but I see what you're saying...perhaps the brief "time on page" could have an effect.