The penis doesn't have the same pores like that on the face, chest, or back. Sure, you can get a pimple anywhere almost... recently, I got on on the side of my hip... probably because of an ingrown hair or something.
The penis can't make zits... the pores don't get inflammed or anything like that.
It can release oil, but if anything... it will mix with the loose skin cells and create smegma-- which is, despite of its gross nature, is a way for the penis to keep clean.
Yes, smegma is nasty... but think of it as natures "own soap" if you will...