If you are sick, shouldn't you be staying home?
In a perfect world? Of course. In this case, plenty of folks spent hundreds on badges, a grand on airfare, and thousands on hotel. With so many "must see/must buy/must experience" things at SDCC, I can see why people would say 'damn the flu' or whatever and push themselves to attend. I've never gotten 'Con Crud' but as I've gotten older I've definitely pushed myself through aches, pains, allergies, stomach issues, etc. to attend. None of those are contagious, of course, and if I were legit sick I'd absolutely stay away from a crowd (caveat, I live about 20 mins. from downtown San Diego & have attend the last 20 SDCC's so that's an easier decision for me than for, say, someone who flies to Comic-Con from The Philippines for their one-and-only SDCC).