I just smelled my helmet after 9 months of commuting and other riding, often with bucketloads of sweat running off.
I can't catch even the faintest whiff, it is completely odor free. Never washed it. How do I do it? (I'm not that clean, my armpits knock out possums at 300 yards after a hot ride.)
After every ride, I take a cloth or paper towel and press firmly on the pads until they are dry. I never considered smell for this exercise, I do it because I hate putting on a wet helmet. Looks like it works for smell too.