Real Estate Agent here and chiming in!
My neighborhood gets zero trick or treaters. I took my kids to a neighborhood in Oak Ridge, NC where I have sold a couple of houses in the last 18 months and they had like 200 trick or treaters. One of my clients always does hot dogs and hot chocolate with a fire pit in her driveway. They have 5 kids, I have 3, all varying ages. So as all 8 kids went their separate ways, I volunteered to drive the neighborhood and keep an eye on all of them. I would do a loop, stop at the house, have a drink and some candy, do another loop. In that time I met LOTS of neighbors, got to introduce myself as "such and such's Realtor", made conversation, and got a couple of "Oh! They loved you! Hubby and I are thinking of listing in the spring. Do you have a card?" Why yes I do!
Free marketing, free candy, free hot dogs, and got to hang out with really cool people all evening. Word of mouth marketing works. Now... was that the intent of the trip? Nope. Our kids adore each other and were begging to go over there. But it really does work. Just be nice, make conversation, be friendly. It's the best marketing around.