The tight foreskin, which is to be left alone, never to be retracted by anyone other than the child, serves the purpose to keep the head of the penis clean, free of bacteria, germs, dirt and poop. That is its main function.
Once the foreskin retracts, and I repeat, it should never be retracted by anyone other than the child, but once it does, then it can be gently retracted and cleaned underneath.
Chances are the child, if left alone, will not retract till he is about 5 or older and well out of diapers.
Even then it does not need to be retracted to clean underneath, until he is a teenager at which time he will clean it all by himself and without instructions. Trust me! LOL
Again, coming back to the child in diapers, the foreskin should be left alone. It will get very tight and the opening in front might get so small that you will only see a pin hole. It is big enough for the child to urinate, and small enough to keep everything else out.
My 6 yr. old grandson, who retracted himself by the time he was 5, never had any problems with poop under the foreskin.
If there was any at all, the sterile urine would have more than likely flushed it out.
Caring for intact penis - no retractionhttp://www.cirp.org/library/hygiene/camille1/http://www.cirp.org/pages/parents/care/