I know recently that Google penalizes your site for selling links, but how does Google actually know if a link is sold or not? For example, how does Google know the difference between an exchanged link, a recommended link or a sold link. Obviously Google may be able to see the exchanged link with two sites linking to each other, but what about when you make a 1 way link to a site that you truly like?
perhaps the googlebot look out for words like "sponsor" "ads". hence google wants everyone to label the links properly with 'nofollow' tags, makes their job easier.
- Their algorithm will check all the backlinks to the site you are linking to. - If the site you are linking to has a large number of similar links. ( similar in terms of anchor text and placement ie. footer, sidebar) Then G has the right to assume that the link is sold.
People can report sites selling/buying links using webmaster tools. I don't really know how else the bot can figure it out. Maybe it has to do with the relevance of sites that are linked.
I am sure that Google system unable detects a link is free link or paid link. Imagine... if you sell a link to anyone, how does Google detects the link that is a paid link? If you buy a link, how does Google detects the link that is a paid link?
Link exchange and paid link are the same and they are penalized by Google. If a site that has too many site-wide and outgoing links, that site probably sold links, exchanged links.
So how does it work when you are selling banner advertisements on a high quality site such as my own, do you still get penalized for selling advertisement?
Not sure how that works but if people sell links for the purpose of traffic instead of pagerank then they can always add rel="nofollow" It surprises me that so few sites add the nofollow link to advertisements. Why let other sites take advantage or your pr?
If you are showing sponsered links at your site and not using nofollow tags, google will surely ban you. --Thanks...
If it is right, then I know why my PR dropped down from 5 to 0 . I had linked from one of my websites to another one. I placed it in my footer. Practically there were more than 9,000 links. If I could know that, I would never do it. I changed my footer and I hope I can get my PR back.
Most everything concerning paid links is just an assumption on Google's part. Even the Google "snitches" that report sites can not say for sure you are buying or selling links unless they themselves bought/sold links then reported you. I really think they could care less if the penalize "innocent" sites for what they "think" are bought/sold links. From what I understand there may be patterns they look for but unless Google is looking over your shoulder, I just don't see how they can say for sure money exchanged hands. I guess they want every link on the web to other sites to be nofollow which according to them is the only way to "prove" to that links are not bought or sold.
If your not using a broker for links and going direct with the advertisers then it would be hard for google to detect whether the link is bought or not. They mostly rely on people reporting sites in or a your site is blatant in link selling then they can pick it up. E.g. You have a list of links to unrelated sites, placed on the homepage.
If some one reports and tells google that you are involved in buying or selling links ... a team will look after your website and network manually !!!