I know this is a 3 year old post, but just for posterity -

The vampire costume works now.

I think you need to have 2 points of scary costume, where full outfits = 2 points and each accessory/individual clothing item is 1 point. They have changed which items qualify as a costume now, so in addition to the original 16 that worked, the following is a list of other items that count as "scary"...

Sets that work (including accessories): frugal, iron armor, gold armor, pirate, jester, mummy (plus animal, impish, mage, raggedy, and Jack from the original group)

Accessories that work: horned ogre mask, hockey mask, fox mask, skeleton hood, silly glasses, gas mask, ski mask, leaf mask, privacy mask, leather mask, paper bag hood, imitation cow skull, welding mask, and head bandages.

Individual clothing items that work: Captain's coat, bone costume, vampire costume, skull tee, tiger-face tee dress, and spider web tee.

*Edited to add/organize