I don't think that you were being too specific. Stilletos and LBD are very common terms to me. Now the kitten heels mentioned above may be pushing it.
The tough thing is that if you don't want to give away too much, is where to draw the line. Both my wife and youngest daughter will put something on and ask me how it looks. And I may comment about color matching, shoe matching, accessories, etc. But my daughter has a habit of asking me in front of someone who doesn't know. So I just revert to the fathererly "you look wonderful today dear". She asked me why I did that and I told her. She still asks but goes "Oh" when I give the diverted answer. But it does keep me from saying something that I want to reel back into my mouth. Grey area can be hard to decide on in a flash.