The thing is, it doesn't even matter what is posted. It's been raided by 4chan which will, if anything, drive up the success of the advertisement - because all it needs to succeed is have people thinking about skittles. As KvP said, once the product has been established to the public, candy sells itself.
People are posting about skittles on twitter to get their name up onto the website - making them think about skittles.
People are seeing other peoples posts on twitter about skittles, without realizing why - still making them think about skittles.
People are going to the skittles website to see the alleged vulgarity being posted (4chan raids, porn adverts, etc.) when they normally wouldn't - once again, skittles on the mind.
People may read about it in the paper ("Skittles home page links to graphic pornography; conservative middle age women slightly irritated") - even more people thinking about skittles.
Heck, there are people like us discussing the ingenuity of the advertising plan - yep, you guessed it, making us think about skittles.