They do it in this way, they first obtain a redirect link like the following http://www.amazon.com/gp/redirect.html?_encoding=UTF8&location=http://www.facebook.com/sharethikana/app/190322544333196/&token=6BD0FB927CC51E76FF446584B1040F70EA7E88E1
then they sponsor this link on adWords, adWords believes it's sponsoring Amazon content and give a lower price compared to sponsoring the real website (around 50% less).
Should I report it, and to who?