The rule is it should look and smell like the inside of a 16 year old boy's gym locker before you're allowed to clean it.
Already at that stage? Gross.
Of course you can clean it. Mild soap and water is always an option. Soft bristled scrub brush. Scrub away. Rinse off the soap, or it can leave residue.
The soft top cleaner we sell can be used inside, too. But honestly, a little soap and elbow grease.