When I was working at my old job, as an asst. manager/buyer at a records store, I decorated the place for Halloween and brought in my framed Barnabas portrait (the early '90s one of Jonathan Frid, used the in color card series.) It got recognized quite a number of times, but usually from people who watched the show originally rather than SciFi viewers. It looked very good with a few store bought cobwebs.
MB is right, at least some of my Halloween decorations stay up all year. That portrait is now over our fireplace at home.
MJ aka CyrusL