It's easier to be misled on IRC. In Real Life body language, tone of voice, and personal history provide context to everything someone else tells you. On IRC they're just words in the ether; it will take time, history, and trust-building to gain that same level of confidence.
One of the really cool things about digital communication is that you can play with your identity, explore sides of yourself that you subdue in polite company. Unfortunately, with that freedom of anonymity comes the very real potential that you will be manipulated or lied to. It's always helpful to remember that you're filling in the blanks about the people you encounter, and there are many more blanks to fill on IRC than in Real Life.