Kim Kardashian's ass is kind of sexy now, because she's relatively young. But in another 10 years from now, it's going to be disgustingly huge. As she ages and her metabolism slows down and her hormones go out of whack like they do for most woman who hit their 40s', that ass is going to get bigger and bigger and bigger. And it's going to sag like a bean-bag chair.
I know this because I'm in my 40's now, and most all the hot girls that I went to high school with that had sexy booty going on, now, some 25 years later, those same girls have absolutely enormous asses and it's absolutely disgusting. I've yet to see an ass get smaller as a woman ages, it only gets larger and larger.