I always bring multiple hospital face masks in my personal carry on. As a former lowly AA platinum, I did not get upgrades on 90% of my flights (typically hub to hub), so I'm sitting in sardines class and there is always at least one or more people coughing and sneezing into me. I wear the masks myself and douse myself with as much hand sanitizer as I can bring on board. Would it be common courtesy for the person that is sick to wear a mask as to contain his/her own germ-infested projectiles? Absolutely. But I have yet to see one person do it, so therefore, I take my own precautions.