Maybe we're lucky, but we've never had visible anything "left over." Everybody's digestive system is different, but poo shouldn't be hanging around in the rectal cavity for long. I don't want to get too graphic (but I will) some people just have softer poops than others and I guess those are more likely to stick around. A warm wash cloth clean up afterward is really nice, and necessary if you are going to go on to ANYTHING else with the penis or hand that was in the anus. You don't want to transmit fecal bacteria (it's there, whether you can see it or not) from the anus to anywhere else. We use a clean rinsing soap, like Cetaphil. Put the soap on one corner of the moistened washcloth and use the rest to clean up the soap. Not a big deal, and he doesn't have to get up.
I do have to add, if you are going to "clean out" the anus and rectum beforehand (we never bother, because this stuff makes me sick, stuff like enemas give me cramps and the runs, so they are out for us.)please, Use a Saline Enema. But,if it works for you or you have to do this due to "left overs" please use a nice saline enema. The rectum absorbs everything put into it, faster and more efficiently than your upper GI system does. Plain water will be absorbed very quickly and too much can actually cause "water intoxication" if used frequently or even once, in susceptible people. A saline enema which uses the same balance as your body will balance things, and not cause problems. I have forgotten the formula for making your own saline enema (but I am sure you can find it online) but Fleet makes a nice one, which doesn't cause cramps in MOST people and will have the proper saline balance, so you don't have problems with water intoxication. There is a tiny amount of a minor "preservative" in it, but not enough to make you sick at all. In fact, as they are prepared ahead of time, the small amount of preservative prevents any "nasties" from growing in the bottle of enema fluid. Some people swear by "soap sud" enemas (we use them in the ER with seriously constipated people) but they tend to make you go and go for a long time. They work on a GI "irritant" idea. They really clean you out. Don't make one of these up, unless you know what you are doing. I believe they can be bought made up ahead of time. But, I'd wait several hours, until you are DONE cleaning out, before even thinking about sex, if you are going to go the soap suds route. Just my nursing training coming in here.
I can be tolerant of almost anything....except Intolerance........and Dairy Products