Stupid kids who bring stupidly cheesy designed armies just to win and make a boring game.
Example, last Friday, a vet I haven't seen in a while comes in with a beautifully painted 2000 beastmen army looking for a game of fantasy. He's been really busy of late and wanted to play me fantasy as we used to have pretty good fun, challenging games that were always close. Anyways, I didn't have my fantasy army with me so he ends up playing some kid who has an 850 point army. Its really busy so they wait about 45 minutes. When they finally start the kid pulls out a tooled out exalted Tzeentch demon, a unit of furies and maybe another unit or two made up of the minimum models to fill out his list. The army had something like 8 or 9 power dice. The game (which lasted like 2 turns) consisted of the kid flying his demon and casting magic and killing the beastman army to death. I don't think the rest of his army even moved. With all the time he had to wait and the other people around he didn't get a chance to play another game, I felt so bad for him, but he took it really nicely, I would have been soo pissed...but that is not the end of it...
After packing up, you know what the kid says..."I am sorry you had to play that army", WTF. That is like saying 'I am sorry for kicking you in the nuts", after wearing steel toed shoes to a sparing contest. If you are so sorry and you know that army is cheesy and does not make a good game, why put it together and bring it in the first place...
I used to roll the dice, Feel the fear in my enemy's eyes
I'm afraid there's no authoritative source for thinking you're an asshole