How Young Is Too Young for Girls and Sexy Clothes?

There has been intense conversation and controversy in recent years about parents who take their little girls and make them in to little beauty queens.

They are helped by the clothing industry that creates clothing for little girls that mirror mother's clothing because they say they want to look like mommy. Unfortunately, mommy understands what it means to show her skin and curves.

Personally, it bothers me greatly that societally we sexualize our girls then get upset that there are pedophiles out there.  I believe we need to STOP sexualizing our little girls.

How young is too young?  When is it appropriate to let girls start wearing makeup, heels, sexier clothes?  

Is it appropriate for ad campaigns like this one to show girls as young as 10 in sexy sultry poses and makeup and clothes?

This question is not just for parents of girls but boys, too, because
your young fellows will be seeing these images too and they will heavily influence how your boys thoughts and opinions of how girls should look are formed.

Please discuss.