Any place that comes in contact with warm but not boiling water is going to be bacterias favorite spot. You should run vinegar through your coffee maker of choice about once per month.
Better kill ALL the germs so you won't get harmed any time!!!!!!!111
(Might affect your immune system and cause allergies, but what the heck, hygene product manufacturers have to earn their money, don't they?)
Regards
Your hygene industry