That's why that many people that RP evil characters are normally bad at it. I roleplay on Garry's mod, on a game mode called Half Life 2 RP. In this RP you roleplay as a citizen from the Half-life 2 universe. To be Combine officers, you need to apply on the forums of that server. Many officers and rebels are bad at RP, simply due to the fact that they have the "lolz i haz gun so i shoot you nao." mentality. They are awful, because the main reason they want to be an officer or a rebel, is simply because they want a weapon and a uniform. They don't want to RP.
There are several officers who CAN RP VERY well. Some even do remorseRP (Where you roleplay your character being remorseful after they are forced to kill a citizen.) There are VERY FEW rebels who can RP well. Even when the officers try to have an 'evil' persona, they RP awfully, and laugh while they kill citizens. I was amputated (A term used in the Half-Life 2 universe when an officer executes a person they imprisoned) by an officer, who sawed my leg off, then shot me while laughing his head off. This is bad RP, because Combine officers are still human. So if you're a human, you probably wouldn't laugh while shooting a fellow human. Overall, the quality of these RP's are mediocre at best.
