Your age please?  

i don't think that it is a bad idea to ask a lady's age from the lady itself.
coz u can easily get their ages by their face.
for example u can see the stars who hide their ages are more concerned towards their looks and all that's why they think that if they tell their original age then people will just think that they are old enough and they will not look them. so they avoid telling their ages.

for me.... its ok to ask her of her age... its really not a bi deal...

Yes it is rude to ask a lady her age, I believe it has something to do with the way someone looks at a woman that has aged well. If you were to meet two women, one of them is srtikingly beautiful and the other was rather homely, instinct would tell you that the homely appearing lady was the older. This is not always the case. I have met a number of ladies that at first glance I would have guessed thier ages around the late twenties and I was WAY off. Another reason it is rude is that most ladies are sensitive about their age. They never want to hear that they look older than they are. Honestly I don't like it when my age is guessed at and I get told I look like I am in my thirties. Other than that I am also at a loss for why it is rude to ask a lady her age.

well some woman may look older yet their age seems to be younger. so maybe it may sound offensive to the women you are asking for?