Social networking will only be as good as the effort you put into it. Sure, some people will visit your website without much effort. Overall the more you seek out people , talk to them, link to them and join in on being social. The more will come from such sites.
I see a lot of people just expecting to get high results with little effort. Today's marketing world is bombarding people with ads. Why people think that works on social sites is beyond me. The data just does not hold ground.
I am mostly talking about the text in which a promotion is delivered.
"BUY THIS NOW BEST TOP PRODUCT, WIN BIG BUY IT"
You would not (or maybe would) believe how many times I have seen this. I prefer to just do something simple. "I found this article very interesting." then link to something I wrote. CTR's are much better. One other thing I found to be a good read was Survival: Currency collapse.
I guess it could boil down to perspective. Make 20 accounts get 5000 friends each. Post tons of ads and if two buy move to the next 5000. Overall I think looking at social sites as nothing but numbers and it's members nothing but revenue just does not cut it anymore. Act like a person get more.
Just my opinion.