Equalist, as much as I too loath girls dressing in the manner you describe above, and wont allow my own daughter to wear tarty clothing, I really don't like the way they described someone's 13 year old child looking like a 'slut'...disgusting, remember it's the parents who should be raked over the coals for what their kids wear, what sort of parent lets their child go out looking like this to begin with?
What's wrong with these people?
My daughter dressed up as Medusa, was hard finding an abundance of rubber snakes last week, normally you find them everywhere in junk shops, but over the last couple of months, they have been sparse.
I attached them all to a black swimming cap with a needle and thread.
Our area is a safe and 'nice' neighbourhood also, though there's no way in hell I would be leaving a group of 12 or 13 year olds to their own devices, without adult supervision.
1) There are some wierdos out there.
2) Given the true nature of "trick or treat"... some kids get carried away with the pranks, the girl who lives next door to us has a couple of bratty friends who I wouldn't let my daughter trick or treat with last night, in fear they would get up to mischief. ...last year, the two girls in question were believed to have taken eggs with them.
Kids will be kids. Parental supervision is your best defence against anything untoward occurring, safe community or not...kids will be kids.
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You will find that these incidents usually occur when there's a lack of parental supervision.
My sons a bit over trick or treating, (he's 16), so hasn't gone for the last couple of years, though agreed to attend the party the night before, so long as he didn't have to dress up...this and could take a friend.
He calls trick or treating and getting dressed -up 'gay' these days.
Everything is "Gay" to 16 year old boys!

... But when he saw what his sister had netted last night, this and wanted half of what she had scooped up...2 full green-bags full, you know those recyclable supermarket bags....
I think he wished he had have gone too.
We had no incidents, we live in a nice quiet neighbourhood.