I think it really does depend on where you live. I didn't see too many sexy costumes in the Deep South, but here in Washington, trying to find a non-sexy version of a costume in a basic box retail store is getting harder. It's easier to just buy bits and pieces of costumes and make your own. I'm not really against "slutty" costumes, but it does get annoying when they increasingly start taking over the aisles every year. It's like it went from being a quarter of adult women's costumes 7 or 8 years ago to being around 4/5 of the women's costumes as of last year.

Dan Savage has started calling Halloween, "Hetereosexual Pride Day" and I think he is quite right ! :)