when im sick hubby uses the lighter to heat up the mouth end before he hits it. i dont like joints anyway, and those would be more likely to transfer germs. i definately agree that if you are sick you should tell the other smokers, and leave it up to them if they want the risk. carry a one hitter with you for those times.
I hardly ever smoke with someone, when I was sick I smoked with matt out of his pipe before, he knew I was sick and still smoked with me