Social Bookmark Visitors
The trouble with submitting to sites like reddit or digg is, the visitor isn't sticky. Sure, they might take the bait, but they're often looking for a quick fix of entertainment.
It seems that a number of the visitors will take the bait, but social bookmark sites often don't deliver the same kind of reader as the one's that find you through a search engine or blog referral.
Someone once said that "...submitting your articles to Reddit is like taking steroids... the effects can be deceiving".