We've been avoiding buying masks from Amazon because they don't do a good job of dealing with fakes (commingling, etc) and they've argued that unlike other reta

We've been avoiding buying masks from Amazon because they don't do a good job of dealing with fakes (commingling, etc) and they've argued that unlike other retailers they're not responsible for counterfeits. What do you suggest people do to ensure that the masks they get are authentic?