Before my wife plays with my posterior, I take a few minutes to rinse three to five times because I don't want my wife to find anything icky back there, and neither does she, but frankly, when it happens, it bothers me more than it bothers her.
I can rinse my bum both inside and out very quickly because I have installed a combination bidet-and-enema system next to the toilet in the master bathroom. A mini water heater that sits on the floor beside the toilet brings the water temperature up to a pleasant 103 degrees F (39.4 C) and two flexible metal hoses take the water to two different nozzles. A handheld sprayer attached to one hose provides the bidet function for the outside cleaning and a very small nozzle on the other hose provides the enema function for the inside cleaning. It is very convenient to be perched on the commode when using either one or both of the nozzles, for obvious reasons.
My anal play with my wife's bottom is somewhat limited. I can insert my finger in her bum hole pretty much anytime we fool around. And, in the last nearly 50 years, there have been six times that Mr. Johnson has found himself within the warm walls of her wectum. Sorry, rectum. And Mr. Johnson is sorry, too. He wishes he could have been warmed in her wectum or rectum six thousand times instead of six.
My wife's anal play with my bottom is far more extensive, with my bum getting a lot more action then hers. She randomly or sometimes systematically inserts things in my bum, including her fingers/hand, her strap-on dildo attached to panties, her old discarded dildos that either don't fit or she doesn't like mostly because I bought them without consulting her, alien tentacles, beads in various sizes on strings, big things, long things, thick things, vibrating things, things that no longer vibrate but still feel good, thrusting things, things that no longer thrust but still feel good, and many other things designed specifically to be inserted in a rectum.
And like @Denise , our mouths are not invited to participate in our anal activities.