I guess it depends on what you define as sagging. For me the breast tissue being subjected to gravity does not really count as sagging. Its where when the skin is getting to big for the tissue when it starts to get less attractive for me, and I would call it sagging. haha It makes me think of...
I love big boobs, only not when they sag. which is naturally only logical to happen to bigger boobs... That's why I generally end up liking women with smaller breasts in real live :P