I don't find the search engine very useful for this particular purpose. There are a lot of items that are suitable for, say, Halloween, that don't mention the word and therefore wouldn't come up in a search. Andi's graveyard props, for example. Yes, you could do multiple searches, for "halloween" and "witch" and "pumpkin" and "graveyard" and "candy" and "mask," etc. But, IMO, most people aren't going to go through that much trouble.