Nope. Not advertising. She thinks she looks good in that get up is all. She probably enjoys the attention that she gets from guys because of it (which is normal for ALL people - to like to get attention from the opposite sex). That still doesn't mean that she is telling you she wants sex. Women are not all consumed by sex like most men are. That is an IMPORTANT difference to take into account. Looking beautiful and being recognized for it is completely different than wanting to **** whomever.
If all that is true, why aren't men advertising? Why don't they all go shirtless, wear open shirts, big beltbuckles, tight jeans, I don't know how men look sexy, they mostly have better sense than to dress like homosexuals! Who of course are definitely advertising --- to other men.
I'd say women dress sexy to signal availability, but we don't mean it. What we mean is that we want to pick and choose. The clothes on women are all about men. I hate that. Unfortunately, a lot of men don't like it that we don't choose them, and this leads to trouble: rape, stalking, harassment, etc. We could probably derail a lot of that by not signaling availability with sexy clothes! Let's do that.
Which is not to say we should go into disguise, like burkas and librarian spectacles and such. THAT becomes all about men, too --- inconvenient purdahs of male-repellants.
You can wear anything you like, Chris, but it makes sense to know what you are doing. If you are wearing a black low-cut evening gown in January while all the men around you are in warm comfy suits, know why you are cold and breaking out in goosebumps. God, I hate the Star Trek uniforms, both series: the women with their bare legs up to the bottom but the males get to wear warm clothes like normal people.