Last year I had to start turning away the kids who were a bit too old and not in costume. Punks.
I had one, about twenty years old come to my door, in costume, he had a couple of younger kids with him. Just a minute of talking to him explained the situation and I gave him candy too.
The two younger kids, about 10-12 years old were actually escorting him on the rounds, he was mentally about 8-10 years old.
You're right though, generally 14 or 15 is a bit too old.
Last year half my doorbell-ringers were ghetto kids who did not know the existence of "please" or "thank you". I corrected them. They did not like that. The phrase "gimme candy, gimme candy" does not suffice at the I Buried My Guns household.
The dichotomy between the regular kids and the feral ones was severe. Some ghetto kids even messed with my jack-o-lantern right in front of me and when told to stop they got attitude, and they were only 9 years old. I surmised they had never been reprimanded, especially by a white person. This year we're just gonna leave the lights off, or I will patrol the neighborhood against the heathens, as last year somebody destroyed a lot of property here on Halloween, and all eyes point to the ghetto interlopers. Frankly, it is a liability letting them near our area.