Apparently mites/lice do like their 'fro, so I just make sure to catch them up and check it every once in a while. Should do this with all chickens really, checking vents and such for bugs.
I did put them in the coop that has the bantams, Silkies, and Cochins rather than the regular laying flock...basically all the chickens who have weird feathering. Figured they were mostly ornamental anyway so they could earn their keep by keeping the garden free of pests. I imagine as long as your chickens don't get too bored, keeping the Polish in a mixed flock wouldn't be an issue.
If they're having trouble seeing because their crest is in the way, you can use masking tape to gather the feathers into a top knot.