//Dave, is there a difference between wearing a good mask properly and wearing a rag or something crumpled you've pulled out of your pocket when you have to?//
Indeed there is. None of the studies which extol the virtues of face coverings say much about the risk of self-contamination posed by untrained, undisciplined people who use them. Virtually nobody follows the rules for wearing a face covering. I have seen them pulled from pockets containing keys, money, cigarettes. I have seen them dropped onto the pavement and then picked up and put on. I have seen them pulled out of bags containing groceries. I have seen them placed on restaurant and pub tables and simply picked up when the user goes to the toilet. I have seen a user go outside to smoke, taking the mask off as he leaves and replacing it after he has stubbed out his cigarette on the pavement.
I would be no different. On the rare occasions I have worn a mask I have found myself doing none of the recommended things to keep me safe from self-contamination. That's why I've kept my use of them to an absolute minimum and now I've abandoned their use entirely.