For me, I don't like it when a guy asks me. It's speaking of sexual services and well, I don't promise anyone a bucket list of activities. Generally, when it happens, it just happens.
You can say that you like it but if your bottom has hemorrhoids or well, you probably know what I'm saying, then women are not going to be as open to doing that with you.
Also, and this is obvious, but clean yourself over and over. Then, if there is a hint of smell, you can always use a baby wipe for a final cleaning. If you're a larger man, it's very important to do this because sadly (and I can say this because I'm a larger woman!), if you're bigger, smell tends to get trapped a little bit in different areas.
So with that being said, some ladies will say that they will do it. Again, though, I have never found it in good taste (pun intended) to ask something like that from a stranger.