[burnished]

I don't really understand what you are getting at. Why is it relevant that you don't feel concerned about spaces contaminated by the germs you personally brought? Of course you don't.

I also don't understand what your toothbrush has to do with this. Please try considering this from the perspective of establishing practice for a bathroom shared by more than one individual: its probably important to know if closing the lid is an effective hygiene technique or not.