Does anyone know if primes are less effected? Just a theory, and not one I'm going to test, but....
Almost every zoom I have used gets dust into the middle elements. Seems to me that the zoom mechanisms typically create a vacuum inside that sucks dust into the lens. However, I haven't, as of yet, had the same issue with any of my primes. Not saying they would be impervious to the color run damage, but just a thought that they may be less likely to be damaged. And maybe I am completely wrong on the vacuum effect. Just going on personal experience.