As a long-time anal player I can say unequivocally that most of us like butts, but not shit.
ANY session or scene with Me involving anal has mandatory cleaning out requirements, and if I see shit, the scene is done. Yes, if you pay for a two-hour fisting and I see shit in the first 20 minutes, you are done. So please, for everyone's sake, clean that shit out!
First, let Me clarify. Ass juices are not shit. Once I get in there and start pumping, that stringent smell of ass cum starts permeating the room, dripping down and coating everything in use. Sometimes that means a light pink or light tan sheen to the lube, gloves, towels etc. That is OK and, although the tan can be a precursor to "friends" is generally accepted. As long as it doesn't smell bad.
As part of your Preparations, I ask always to have the groin and anal area shaved and hair-free. Smells get trapped in hairs and are really not fun. This can be done while you do your "Cleaning Out" routine. As a pleasant bonus, use flushable wipes (but don't flush them, apparently) and wipe the area just before play, so any errant odors are eliminated.
There are two levels of "Cleaning Out" that I recommend, depending on the depth and severity of play that is anticipated. For prostate play or "shallow" play, a bulb enema can be used about an hour before and again immediately before play. For deeper play, you gotta run a bag! Whichever method you do, make sure you practice a few times (before the day of play) so that you know how you will react. Nothing mars a pleasant playtime like intestinal crampage!
When you "run a bag", you fill the enema bag with warm water, run it into your anus completely while either laying on your side or kneeling with your head down. Hold as long as possible before evacuating. Repeat as necessary.
Run a series of bags until the water runs clean. Practice ahead of time, as you will need to know how you react to enemas and if you will experience cramping and so on. Wait an hour or more then run another bag "just to make sure".
If you have completed the above, waited an hour, then checked with another bag and are completely clear, then you are ready for play. This takes practice to know timing.
Another option, for those who play a little more often, you can get a shower system to run the water for you. Again, the temperature is super important, and make sure the pressure isn't too high, else bad things can happen inside. There are a few systems available that connect either to the toilet or the shower. I highly recommend the shower system, for the simple fact that toilet water is always cold! Yes, it may be more convenient and can double as a bidet, but the temperature is really critical to avoid cramps. If the water were even room temperature, it would be moderately acceptable but toilets are just. so. cold!
My favorite setup was a showerhead that doubles as a handheld shower, and then we just replaced the handheld head with the enema heads. If you look carefully, you can find longer hoses so that you can reach a little easier, especially if you like to kneel while running the water.
Some people find it easier to limit their diet the day before and day of, so as to maximize the experience. Trust Me, your top will appreciate the effort and reward you enthusiastically!