Omg, seriously? As long as your bowel movements are normal (aka, you're not severely constipated or have a GI disorder), the anus is clean. There is warning that occasionally you may get a very small amount fecal matter (on the condom you should be wearing), but that's not the standard. That's a rare occasion. On even rarer occasion, a person may ......
Because feces are not typically stored in the rectum, the part you can reach with a finger or a penis. Stool is stored in the sigmoid colon and is only released into the rectum at the time of a bowel movement. While there may be trace amounts of fecal matter remaining in the rectum, in a normal healthy person, there would not be large amounts, ie: ......
when fingering anus there is no feces in yaoi manga