Facebook have some rules about where and how you can launch contests through them. Facebook promotional guidelines. So many marketers seem to forget about this... Just saw this example. This page only has a hundred fans so maybe they don´t care if they get shut down but it still seems like such a shame to me.
Example of how you CANT build a contest (this example is a spanish site)
Pay attention! Facebook can shut down your page anytime if you break these rules. You MUST use an app to launch a contest and you can NOT require people to comment or like things on your page in order to enter the contest.
I´m putting this picture in the extra large size even though it doesnt fit the blog but I really want you to see what it says so we leave you with zero doubts.Tweet