A picture paints a thousand words.
Of the centrepins I own, I find the Zeppelins to be the least affected by accumulated gunk. The design is such that nothing gets near the spindle or bearings in normal use. I've also never experienced that horrible gritty crunch of a little bit of grit/sand with the Zeppelin.
As it has no screws through the backplate, and no joints/seams of any kind on the spool, I find it an absolute doddle to clean. I'm not averse to rinsing it under a tap. I just make sure to keep the bearings dry. The ratchet mechanism is usually greased. However, as the reels are so well put together and finished, I find that there's little need for it. I found that greasing the mechanism just caused gunk (mostly maggot maize flour/sawdust/bran) to accumulate.