Why? Mostly they are a punch of spammy links (Pligg sites) or nofollow. Links (auto or manual submission) from the ten million and one crappy Pligg sites is the kind of stuff Google will either ignore (if you're lucky) or that Penguin will eat for breakfast. Be creative, come up with a different link source.
I agree. You're better off spending on an SEO expert or an individual who can manually build links for you. Have a good day!
I agree with the other comments here. Manual submissions always tend to be better than paying for automated services when it comes to link development.
Google loves slower link building, just try organic manual link building, keep updating your webpage everyday.
If you are doing social bookmarking then please use unique description, it would help a lot, this thing can be used in directory submission too, I would say.