Once Patch 2.4 goes live, we will most likely be able to queue up for all of the major battlegrounds as premades. There will always be PUGs, since even the three battlegrounds that allow premade groups to play have them. Sideways of Korgath posted a thread on the official forums on the most annoying PUG player archetypes. The original list included:

• The Aloof - This guy appears to be guarding a flag or, but the chickens at the farm in AB are actually doing a better job. It's hard to say whether he's AFK, chatting in vent, or just didn't get enough sleep last night, but a guy caps the flag behind him and he doesn't even notice. If he's in gulch and the enemy flag carrier runs by, he just keeps on doing whatever it is he's doing as if nothing happened.
• The ADD - This type of player just can't live with less than continuous action. The concept of defending a flag is foreign and distasteful to him. Therefore if he is defending something and no enemies show up within 30 seconds, he moves on despite the fact that he is leaving the flag unguarded for a friendly neighborhood rogue to ninja.
• The Instance Mob - This type of player makes you swear aggro generation applied to players. He simply cannot understand why he hasn't been able to kill anything despite the fact that he put forth his best damage attacks against the protection specced shield wearing warrior that had 2 priests, a paladin, and a druid healing him. Much like I expect Rend Blackhand or Nefarian would, he attributes his ineffectiveness to inferior gear.