Are you wondering that in case a site linking to your site gets penalized for purchasing links, will the penalty affect your site?
Google Webmaster has just uploaded a video citing the answer to your question:
You can ask similar questions on the Webmaster Help Forum:
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- More videos: http://www.youtube.com/GoogleWebmasterHelp
- Webmaster Central Blog: http://googlewebmastercentral.blogspot.com/
- Webmaster Central: http://www.google.com/webmasters/