I am curious about this....

It's the butt cheeks we look at, not the anus

guys have told me that they like woman's bums because it reminds them of boob cleavage. i like mens bums because its so much fun to spank them!

for girls, estrogen is stored in their butt cheeks (true) and since that is the female hormone, the male takes it as the female has more of this essential hormone. smack dat

I'm not attracted to that in men mostly because they wear stupid baggy pants. WHY DO YOU DO THAT?!!

LOL I think the same way. I don't care about bums

Well, i'm totally NOT interested in other peoples ass/butt.
i know my cats often smell each others ass, but i'm not interested, i'm interested in the overall prettyness.

There's also the unattractive ass as you can probably imagine. Fast food loving fatties that wobble when they walk.
But the reason why we appreciate a nice ass is:
As a male looking at a female - the ass displays a healthy set of child bearing hips. Preferably balanced well for child birth and mobility. Hip to waist ratio, and the ass is the centrepiece of this you could say.
As a female looking at a male - the ass is ideally smaller, so as to display athleticism and efficient pelvic thrusting ability.

We don't think of these things conciously tho. We don't need to, we just need to like it for us to act out our instictual intentions.
This frees up our thinking power to enable us to think of what TV show we are going to watch that evening.

Actually I can think of a couple of likelier dirtier places on our body that we actually use more.

I like ass very much and who ever said that yea I think ur thinking too much about what comes out

you like ass sexy ass so do i

You're focusing too much on the biological function of this area of the body.

That's pretty funny people. But ya, its the cheeks not the hole. And anyway, people do wipe after pooping so its usually not dirty anyway. And I suppose your not a fan of sodomy

See how animals like their asses too (dogs for example)...

It's something beyond comprehension, it's something that is built-in in our brain and it works on its own just like breathing or heart beat. Even though we can control outward displays of inner excitement over sexy ass (i.e., not jumping and grabing it lol), excitement that you feel is still fired up non voluntarily by your brain. Apparently no specific logic here.

The ass is not a dirty butthole. There. Rest easy.