Sometimes we get a little paranoid about cleanliness. I've been reading more and more in different places about why our children have so many allergies. They had no opportunity to "play in the dirt". Much of the bacteria we are so afraid of is actually good for us. We shouldn't be killing it.
I have two strong plastic grocery bags that I have been using for more than 20 years. Sometimes they get used several times in one day. The get washed when the spirit moves me. - Not too often.