Think about it for a second. If you got poop on your arm, would you simply wipe it off with toilet paper? Of course not. You would use soap and water. Your asshole is no different. After you evacuate your bowels, get in the shower with a washcloth and go a knuckle deep and clean your rectum.
The benefits are many, including no skids marks or ass plume odor vapors escaping. When I was 19 I used to do this really cute blonde doggy style but her ass stunk all the time so I would lean to the side to try and avoid the odor column rising from her ass cheeks. I think about her and how badly she could have used this technique.