When I am shadow spec and theres no enemies about and a rogue asks for a heal, I always give a heal. I'm not a tight arse like some of you, I play in an MMO so I expect to play together as a team. If I didn't want friends I'd go and play a 1 player game somewhere. I think you need to get over yourselves a bit.
As for people yelling for heals when under attack, they can easily be thrown a shield or their enemy feared for them by you. But I guess you selfish people don't do that either right? Cause it might hurt your score on the damage chart. But yet I bet when a Rogue starts bashing you from behind and your friend Rogue that you were rude to earlier doesn't bother stunning the enemy Rogue to keep you alive.. no he just goes full blown damage and let's little shadow priesty die am I right?