I used to think there should be an age limit, I think i officially stopped trick or treating at like 13 or 14. I live Halloween though and always did so I dressed up and trotted around with my little siblings to help keep an eye and make sure they were safe and didn't get too scared because we did have a few houses that often provided "tricks" with their treats.
Most of the adults tied to give me candy too even though I wasn't carrying a bag, some flat out refused my attempt at just saying I was chaperoning and not trick or treating. Got told by a few that I dressed up and that's the rules, I got candy without trying just because I wanted to have fun and spend time with my siblings.
I remember a few people giving my dad candy when he took me as a kid because he always dressed up with us. He even stayed back on the walk way as we walked up to the house and the old guy giving out candy yelled out "Hey Wolfman!" my dad looked up as he was dressed as a werewolf and got a reeses thrown to him with additional compliments on his costume.
All this to say is I don't think I'd give any side eye to anyone coming to get some candy, sometimes adults need a little pick me up as well and it just used to be fun seeing all the different costumes and creative stuff people would come up with or randomly scaring a couple older kids just by opening the door with whatever creepy costume I had that year.