ywn shows women in their photo albums and perhaps news items, so it seems that ywn shita is to allow tzniusly dressed woman into their pictures. if you dont like that, there are plenty of other frum websites out there.
i have adblock (which i recomend you get), so i dont know which ad you are referring to, but i assume that it has a tzniusly dressed woman in it. if it dosnt then you takeh have a good point.