I've searched the forum, and I can't find anywhere that this has been discussed. I have a site that used to do quite well in StumbleUpon, but got hit hard by Penguin (no penalty, just badly affected on many queries), and lost the Stumblers seemingly as a side effect of losing the Google traffic.
Stumble offers "paid discover", where you can pay to have your URL put in the normal stream of sites people are stumbling. I would happily pay for this and see how it works, but I'm wondering if Google can detect this and how they view it. I don't see that it's really any different from Adsense, but then I'm baffled by how Google defines "paid traffic" or "paid links" sometimes.
Has anyone tried this (or a similar model with another company), and if so, did it seem to make any difference to Google?
Note: I realize Stumble doesn't help my SEO. I just want the visitors, because they convert on this particular site. I'm pursuing targeted traffic, not rankings.