I am not sure that there is "proof" especially over any extended period of time seeing as these things always change. Over the short period I would be very careful. That is the way it is meant to be used, however, many people are misusing it.Originally Posted by charlesgan
Because many people don't yet know about the rel=nofollow concept, you can really cheat your link partners and turn recips into one way links this way. However, when they learn what you have done, it will come back to bite you.
The biggest application I have seen is in blogs. Where comment SPAM is ridiculous and people are trying to tell others that they have "nofollow" so its useless. Unfortunately when you deter SPAM and don't prevent it, it only tries harder.
I hope this helps.
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