One thing that would help me would be the ability to just block a whole server.
In my battle group, Hakkar is well known for being generally useless at anything and people from Blade's Edge andAzuremyst are, in my experience, more likely to be douchebags....

The problem with sorting by a gear level is that you can fudge it to an extent. It is already built in the dungeon finder, so that you have to have a certain ilevel before you will get put into the heroic IC ones. Now for the part about fudging it-- I was healing H HOR and the tank was having trouble keeping the mobs under control. I thought "hey he has the GS for this maybe he sucks." Then I inspected him. He was in PVP gear, and when asked he said he could tank in it "just fine." We disagreed with him...
anyways TL:DR gear is a horrible way of judging players

I'd block a whole server like that. The Nightfall battlegroup is plagued with the Kel'Thuzad server, a group of peole convinced that they are God's gift to WoW. If a random group has a member from KT, 99% of the time it will be a drama filled experience.

However, rare occasions include KT people being helpful, friendly, and curteous.

Without Blizzard going through and marking every piece of gear for what specs it belongs to, there's no good way to determine what kind of gear someone actually has. What if they have a DPS set that's entirely from H-ICC25, but they're queued as a tank in ilvl200 blues? What if they're DPSing in PvP gear? Et cetera.

I'd kill for the ability to block people from my whole server. Khaz Modan is full of elitists pricks. Hell, we are the # 1 server on Wowjackass.com. If it wasn't for a handful of people I'd server transfer in a heartbeat

When I saw "more stringent instance separations", I initially thought of an option to choose groups where everyone comes from a different server. Chumminess between players familiar with each other is often irritating, but whenever I find myself ported into a group with two or more guildies, I'm more than ready to /quit.

Yes, I have seen a sudden rise in kick votes recently, and most have come during instances when two or more members knew each other. In one there was a sudden and unexplained vote to kick a healer who had done nothing wrong (it would be nice if you can't initiate a vote without supplying a reason), and when I voted no I got a whisper that I would go next if I didn't support the vote. I refused again but the healer disappeared. Since they had apparently burned up their one chance to kick I guess I was saved at the expense of the healer, and yes, we had to wait around for quite some time for another one to appear, all because they didn't like the shade of the original healer's bark, I suppose.

As a brief canard, I was in the LFD for FoS hc the first day it came out. I figured it'd be tough but that I was used to healing ToC 25 and whatnot so it'd be at worst, on a par with that.

Enter a group with 4 members of Bloodline EU. As healer I proceed to die on every boss except Ick as far as I can remember, but they were supportive and encouraging. I felt naked without Grid and all my other addons. Eventually we killed everything, including HoR. I d/c'd one boss and they waited around 3 minutes for me to get back and healers aren't exactly rare on this battlegroup. We got "don't look up" the first day it was out too, so I was really happy. If it was a complete PUG even with some nice individuals, I doubt we would have done it.

"and people from Blade's Edge and Azuremyst are, in my experience, more likely to be douchebags...."

But i'm not... :( I'm one of those easy-going people that will put up with different play-styles and try to go with it. Even if it's a gogogo warrior tank.

Although we do have idiots on our server. They are loathsome.

Recently, i was in a pugged run for Oculus... at the last fight we had a wipe, because there was no co-ordination in the group. How can the healer heal when people go anywhere? No matter, the healer was kicked. :( I don't recall who was from where, but that was wrong.

This won't matter in Cataclysm because raiders won't be running Heroics. While Heroics may give some Valor points similar to daily frost emblems today the cap on Valor points will mean raiders will hit the cap from raid content.

Of course the whole point of triumph/frost dailies was to get raid geared characters to carry new players/characters through the content so we will see how long that lasts.

Barely twenty minutes ago I had yet another H HoR group break up during the opening waves, yet the first time we wiped--heals said "Lag spike"--it was a dpsing Shammy who was voted out (and I didn't even have a chance to vote "no" before the vote passed). When we wiped the second time, the healer was the first to drop group, without even taking the time to offer up another pathetic "Lag spike" excuse.