Do you change personality when nobody knows who you are, and you can say your opinions without people judging you by your outside? For me, yes. On some sites and forums, I change into a sarcastic, cynical bastard, cause it's in some cases enjoyable to be a smug jerk and that's how I feel on the inside most of the time. I'm not the kind who yell out idiotic hate and stupidity and write like his keyboard has glue on it, but the kind who likes to argue with the aforementioned glued idiots and prove how they are wrong in their aforementioned hate, cause it's entertaining to read how they angrily misspell every word in an attempt to insult me, while I spell like someone who got an A+ in writing and wants to brag about it (which would make sense, cause I usually do).
In real life, my outer appearance stops me from being this kind of person, which drives me nuts. On the Internet, the ones you talk with gain respect by your intellect or your wits, while in real life, most of the first respect and impression comes from the persons outside, which is a sad fact.