I dont care how old the kids are. As long as they are polite & at least say Trick or Treat.
We lived in a neighborhood the last few years where the houses were pretty close together. And we always got hit hard by the ToTers. However one end of my street hardly participated. I thought it was pretty sad. Looking down one end & seeing all the fun & then the other way was completely dark.

Come on! It's Halloween, go buy a bag of candy or 2, it doesn't even have to be the good stuff. Just let the kids have some fun!
Right now we are in a neighborhood where the houses are also close together & from the looks of it, everyone is into it. All the houses have had some sort of decoration up for almost a month already. So we went & bought a lot of candy to give out.
We will go out early with DS (3) & be back in time to give out candy. I think DS has more fun giving out the candy then ToTing himself.
Next year we will have to hit another neighborhood. We are building in a small upscale neighborhood, where there are only 8 homesites in the gated section. So not to much on the ToTing.
So we will probably go to my Mom's neighborhood & let DS ToT there. We will of course be with him. I hope no one jips DS because they dont "know" him. But if we dont go to another neighborhood, there wont be much ToTing fun for him next year.
It is once a year. I bought $50 worth of candy last year & ran out twice, with DH or I running to the store for more. The 3rd time we ran out & it getting close to 10:00pm, we finally shut off the lights, but I know a lot of people kept going.
This year we will probably open the door until close to 10:00pm again. I get a kick out of seeing all the kids in costume & excited.
I dont care of you are 8 or 18, just be nice & say Trick or Treat. And a costume is preferable. But we dont question why they are not in costume. I know a lot of kids who could not afford costumes, or risk "ruining" any of their clothes by "Halloweening" them. So we just smile & hand out candy to everyone!