Board Thread:Fun and Games/@comment-20013779-20141031201514/@comment-24577221-20141031204239

The Halloween skins are in the game's application data in your personal documents directory rather than in the game's own data directories. The details depend on which version of Windows you're using, but will be something along the lines of AppData/Roaming/BBB/MySingingMonsters/1/downloads. If you look for a directory named MySingingMonsters, that will probably get you where you need to go.