This discussion reminds me of those that complain about others drivng habits.
"how come this person is drivng soooo slow. Don't they pay attention to what the speed limit is".
"I can't believe this person is trying to pass me. What are they in such a rush for."
"the light is red! Come on, get a move on."
Too bad everyone couldn't just be the same as ME, then the world would be a much better place!
(insert eyeroll emoticon here)
If peoples behavior bothers you, maybe ya should consider not attending populated events where you just know there will be some that will act in ways you don't approve of.
Now if someone is acting unsafe, that is a different matter, and for the most part, the crowd is good at capturing that, and if not, that is the real reason for security (some sercurity folks should be reminded that this is really their real function).
I guess I have been guilty of irritating fellow attendees at times (not sure about them being deadheads) by acting in ways they felt was inappropriate. I have been known to really get into certain song(s) and break out in what I would loosely call a dance (HA! body gyrations more like it), I have been heard at times singing along with others, I have yelled out to the band, sometimes just yelling one or two of their names for them to hear (no whistling though, but mostly probably because I don't know how to loud enough for it to be heard very well. Probably a good thing!), I have given random high fives and hugs during the start of some songs, and I have also just stood quietly, soaking in the entire experience.
Lots of factors play a role on behavior, the peeps surrounding, current headspace, how long it's been since the last show, and of coarse, ehem...so called enhancements (alcohol and other adult treats, which we all know has different effects at different times).
I don't think it's very reasonable to have the expectation that everyone at the show is going to act the way you want them to. And to try and affect behavior in others by wearing shirts or passing them a card that essentially tells them to stfu will make matters worse in as many peeps as you hope to improve.
To each their own though, and for those who might be standing near me at the next show, be kind....please....my behavior is not meant to impede your good time. You just may find me offering you a water if I notice you are thirsty, or an orange to share with your loved ones, maybe a glowie to wear if you would like to be festive.
May the light shine away the darkness.