I don't think hikers have a higher rate of brown blazing, just that we tend to talk about things that others may never bring up in conversation. That being said, I brown blaze cotton roos all the time, because it sweats and sticks more. Poly roos tends to streak easily, too. My wool are great, and as long as you buy the black ones, I tend to not notice as much.
Keep yourself clean and change your roos daily and it's not too bad. Filtering water helps, but for all of you "o naturals" I think you're nuts. My roos are like an insurance policy, just another layer that is changable in case of brown blazes.