With a bounce rate of almost 100% no clicks on ads which fuel most websites and not much pageviews except the one stumbled, stumbleupon traffic is useless. Earlier this month I had one page with a picture on it stumbled from another website. It lead to 30gig of downloads of that 1 image and more than 30 000 uniques but guess what, I did not make a dollar and the site had enough ads on it. Some people claim they make money out of Stumbleupon but that could be just one in a thousand. Stumbleupon can also get your adsense account blocked as I have learned the past couple of days by fellow bloggers. Adsense said its because they had to many invalid page views or something. The point is Stumbleupon will not turn traffic into target.
[...] traffic is completely useless. They just stay for seconds and never buy anything. See: Fromtheold