Everybody wants a raise on their salary, but sometimes they didn't evaluate their performance prior of asking for pay raise. Perhaps an article on LifeHacker can be your guide about when to ask for pay raise. There's also a link to another site which discuss this problem as well.
The situation here is very contrast with what happen in our People's Representative Counsil and People's Consultative Assembly. They were highly paid and still they urged to get more by making their own rules. Yet their work is often don't accomplish anything. There are a lot of discussion leading to dead end. It would be better if the money that were used to pay them is being used for another purpose, for example education.