I have read that buying backlins to my site and offering to sell backlinks from my site can hurt my ranking, pageranks and possibly other ways. I do not understand how Google can tell if backlinsk have been purchased by me to create links from other sites to mine or whether I have sold links from my site to other sites. If this buying and selling links can hurt my site I want to know how Google can tell the difference between natural linking an paid linking, after all they know nothing about the transaction or are they Big Brother spying somehow?
They may not discover it .... but it will hurt if they do. In one of their tools, they ask webmasters to report websites that buy/sell links. You wouldn't do it if you were me ... but you are not me ... so take your chance if you want.
They can discover it. A site with no links and with an increase of, say, 100 incoming links a day sounds suspicious right?
A lot of people argue that Google can't detect paid links but no one realy knows, and Google won't tell us either. But it's not the paid links that's the problem, it's the paid links that pass PR that Google doesn't like. As cocaolafun said, as long as you use NOFOLLOW on the links, Google won't mind because then you're selling traffic, not PR.
its very simple for google..A person who is selling links to you will obviously be going to other buyers...and when same kind of links and same kind of content in different websites will make the content suspicious..So google can really hurt you in case you buy blog posts....I have my friends who bought payperpost links are now crying as google snatched their PRs...