From my previous experience, I know that Google penalized paid links. How? I am not sure to give you the right answer answer but a look at the article from Matt Cut of Google
about "how to report paid links" may put us on the track.

Are paid posts like paid links?
Disclosing compensation for promoting a brand could be the starting point to create a win-win situation for bloggers ,brands and shoppers:
- brands pay for promoting and get ROI
- bloggers are paid for writing articles
- and shoppers get access to the RIGHT information
This win-win situation can be realized via a platform where bloggers are free to promote the brands they really like and share the advantage with shoppers.

Yes it is possible!