Most likely door handles. If you think about it, when you or your parents clean the house, no one ever cleans the door handles. Disposable wipes get thrown away, and washing areas probably have germs at the bottom of the sink but it’s not like when you wash your hands you touch the bottom of the sink. And surfaces treated with bleach is of course not the answer. Bleach is a very strong substance literally made for getting rid of germs. Hope this helps you! :)