Ah, good news, for a change. I've always said that entering contests can translate to sale$, which is the main reason why I keep creating & hosting them. Takes a little effort, but when members report back with a success, I feel it's worth my time.
Like CJ says, a sale can happen whether or not you win or place on the contest leaderboard. Visitors & potential buyers do scroll through the list of contests in varied stages of completion to find subjects that interest them...and buy.
It also helps if both the host & participating members plug the contest, as in sharing the link with others, which adds up to lots more views & possible purchases.