You can turn negative things to positive with contests, you just have to be creative. For example, you can use a clever contest as a great way to correct an error.
An author even used a contest to get herself out of a sticky situation. Mystery author Cecelia Tishy discovered that a full line of text from her new novel had been omitted from her printed books. She and her publisher didn't want to tuck a correction sheet into the book. Instead, they reasoned, since the book is a mystery, they invited readers to solve the mystery of the missing line. Dowling Press offered a $500 prize to the reader who found and provided the best missing line.
For more great ideas on how you can use contests creatively see Special Report #18, "Clever Contests That Will Tempt Reporters to Call"