We have like 4 children in our neighbourhood. If an adult showed up at my door in costume, I’d be thrilled to get a visitor, give them candy and offer them booze (it’s also common in my area for homes to offer drinks to parents who are chaperoning their kids).
On a similar note, when my son was about 7, my girlfriend at the time (who was 28) came with us in costume and and went up to houses with him with a candy bag and collected treats. The first couple houses, I actually felt like “this is a little embarrassing” but people just gave her candy and alcohol and I was like “You know what, this is fun!” I realized I was being a stiff adult and should just get over myself (a beer and a couple cup of hot cider with whiskey didn’t hurt my attitude either).