In 1984, Adidas was the Official Sponsor of the Olympic games, but Nike decided they would take the short-cut and buy up billboards, bus ads, and television spots in large numbers.
Nike even put pictures of their athletes doing what appeared to be Olympic events.
Nike never used the Olympic rings in any of their ads and didn't pay the $45 million to be an official sponsor; however research after the Olympics indicated that people actually thought they were the Olympic Games sponsor.
This is called ambush marketing. Based on your research is this illegal, unethical, or just plain smart business? What are things companies can do to "combat" ambush marketing.