I agree with Rob, we do that in the toilet in our camper.
As for the reason it's happening (and this is only a guess, but it makes sense if I can figure out how to explain it) -
When my kids go poop, they go completely, and rarely have to wipe more than once. Usually when they wipe the first time, there isn't even anything there. Poop is covered with a thin layer of mucous, which helps it slide out. It also acts as a lubricating barrier kind of - and that helps eliminate the mess.
If you have to wipe more than that, you may not be going completely, or your mucous may be more mixed in rather than on the outside, adding to the skidmark factor. OR - if you don't have floaters, that could add to it too. Also, I think the softer the consistency, the mushier and more skid prone your poops are.
Wow - poop science. That was fun.
(LOL! I just read that to my husband for kicks!)