Asa tank since 2007 (started as a healer before that) in many MMOs I find maybe about 2/3 to 4/5ths of the PUGs I do have no real problems with attitude.
I remain relatively quiet - unless its a raid then I let others do the assorted talking, take it all in, and offer a few short friendly replies.
When I chat, its more or less social, or noting a mistake I made. I rarely call out others, but will call out myself. That doesn't mean I can't see it when someone else goofs up. But I presume they know, and they don't need me telling them. Nor do I need me getting stress by holding it against them.
I also toss in a few emotes here and there. /wave /panic and so on. The silly of friendly ones. I used to often wave hello or goodbye at bosses for example, before the pull. Sometimes when I feel a need for humor, I've marked myself as the kill target (when it was a one mob pull)...
- These assorted things MOST of the time keep people calm.
My bad runs occur when I'm not yet invigorated enough to start up before somebody else pipes in with a negative... or in the very rare moments that a real jerk gets in and just starts raging - because they do exist.
Back to raids: I usually play down how much I know a fight if I do know it. As I'm open to trying other's strats I'll just remain silent if someone has one, and go for it. If no one has one, then I will pipe in with stuff. This tends to result in my getting invited back or put on people's friend lists. Often people start to feel I was great at leading something when all I did was stand at the front and mark things... but without being pushy, so everyone just felt comfortable.
Now when I'm not there as a tank... my play style is fairly similar, except I don't stand out front and basically let the tank lead things regardless of whether I think their making the right or wrong calls. I DO see a number of tanks get edgy. But I also see a LOT of DPS and Healers raging on other tanks. More than they do on me. And often in situations where I know they should not be...
That said, one that really irks me, but which I tend to remain quiet about, is that when I am there as either a tank or healer... the other person in that, the person I am healing or the person healing me... will often start whispering / telling at me with complaints about the DPS... Or if I'm healing... with complaints about the tank. But when I'm tanking they rarely whisper me about the healer... Its like some people want to start up a high-school drama thing, and feel I would be perfect to go along with it... /shrug.