If they're new then it shouldn't be too bad - the mistake people make is not servicing them. I think every 10k you need to wash the cotton and re-oil it with the appropriate stuff from the manufacturer. It lets in the smallest parts, which stick to the oil or PTFE and slowly build up as gunk inside the charger.
I use a paper filter as I prefer to open up my charger and see it clean in there - I change them regularly. Paper filter = happy charger.