Holloween is a scheduled event. Depending on where you live, it happens every year, on a set day (or days, as sometimes C-ville has "rescheduled" trick or treating to weekends when Holloween falls during the week) and you can opt out of participation (turn off lights, not at home, all that jazz)
Door to door salesman, missionaries and (because they do the same thing) telemarketers do not arrive on a scheduled day for such things and you can't "opt out". Many times they will show up (or call) regardless of no tresspassing signs, no solicitation signs and no call lists. Even if you don't answer the door or pick up the phone, it's still an annoyance and an intrusion on you're day.
Plus, they can be pushy. I know I've told the story of the Morman boys and Southwest. The fact that I yelled at them to leave from my front porch, wrapped in a freeking towel, and yet they come back when I'm clearly just trying to get my dog?
The point is Holloween, you know it's happening, you can choose to participate or not, and you won't end up running after your dogs, half dressed and your hair is still wet, because some idiots came on your property while you where taking a shower.