What do you think of teens trick or treating?

Since Halloween is coming up I thought I'd ask. I'm a teen with no younger people in my life (youngest in family and friends) so I stand with it's okay. However last year someone refused to give my friend candy becasue he was "too old", he was 16 at the time (he does look a little older though). They still gave me candy, and I was 15. I was just wondering stances on this, because I feel like everyone should be able to celebrate Halloween if they want to. Also aren't teen-agers still kids to an extent? How old do you think is too old for trick-or-treating?

(answers are worded funny due to character limit)