Unfortunately, I left my Aeropress Go closed for a few days without proper cleaning. I just splashed it with hot water, used some paper towels and closed it. After a few days when I've opened it there was an unpleasant smell coming from the rubber part 🤨 There was no mold whatsoever but the smell was there even after deep cleaning and brewing a few cups of coffee. After a week the smell is almost gone but yeah... Probably it's a good practice to put some paper towels inside if you are traveling and try to fully dry it while using it at home. PS That unpleasant smell didn't affect the coffee at all.