Pretty soon. I was seeing 12 year old girls wearing slutty clothes for their regular day, where you could see their thongs coming out of their pants, so I can't even imagine how they dressed for Halloween. The slut train is still going, but you can get on it if you want.
I'm turning 17 in 3 months and I'm going as things 1&2 with my cousin. I'll have on a long sleeved shirt, black and white striped pants, a tutu, and boots. The only skin I'll be showing is my hands and face. Forget the slut train, I prefer the free-candy-from-old-people-who-approve-of-my-decent-outfit bus!
I thought I was cool at 16 wearing a "play boy bunny" costume for a Halloween party at my friends house. Bought it, looked fantastic. Ended up putting a long sleeve shirt and baggy leggings on underneath it before even arriving at the party because I felt uncomfortable being dressed provocativally in front of people. Needless to say, I looked like an idiot. But oh well. I still haven't worn a sexy costume out anywhere. I wear them occasionally for my boyfriend in the comfort of the bedroom but no where else.