I am learning of more and more people (my husband included) who do not wash their new clothes before wearing them. My dad had told me long ago to always wash them because of the chemicals they use to preserve the fabric (formaldehyde for one!) and because I never knew how many people (and what type of personal hygiene they had) had tried it on before I bought it. I try to get my family to do it, but am not always successful - except with Avery's and mine since there I have more control. Of course, ALL pre-owned clothes are washed before they are worn!
Anyway, I included some links for reading on the subject.
http://www.associatedcontent.com/article/233417/should_you_wash_new_clothes_they_could.html
http://www.minti.com/parenting-advice/1066/New-Clothes/
http://organicclothing.blogs.com/my_weblog/2007/02/removing_odors_.html