I think the biggest problem with evil in games its 'I WANT POWER I CRUSH YOU'... which is boring to me. Most video games I usually also end up chaotic good (on personal level with lawful neutral tendencies - there is a reason for law and order, but I know better, right? Right!).
But as a DM I have to play evil characters and actually they can be fun - a lot of fun. The thing is if you have more than the simple wish for power and greed it can be a very fulfilling new experience. I remember having a player in my game who was protecting a town from demonic cultists meet the leader of a faction that was serving devils. The player could be called chaotic goood guy, who just wanted to stop the monsters and through the dialog with the devil-worshipers I managed to convince him that they are actually just doing what is needed - not because I offered power, but because I explained their motiviation from a personal convinction and experience that drove the leader and the devils to commit heinous acts that in their experience were sadly necessary. Something the leader didn't enjoy doing, but he was certain that no other way would lead to a final victory against the great threat of demons.
Like I said, it was far more fulfilling than tearing a man's arm of because Shadowheart can then drop a lame joke. And 5min later I had to convince the player that without hope and being a guiding example for others victory would be meaningless because he had to talk to the lawful good cleric he usually confided to... and I convinced him again. That's the reason why I also now love playing demons of seduction/manipulation...
Also all of my players loved the mini drow campaign although they usually all play the good guys. I told them its a short one so feel free to kill each other, scheme against each other and everyone else - what happens in the Underdark stays in the Underdark. They didn't go after each other openly, but they enjoyed for once to be scheming bastards that put their own interests above their party. And they now want to return to that mini campaign. But again each character had their own motivation beyond just 'lets be a murder hobbo'.
As I said, playing 'evil' can actually enhance your experience and give you new perspectives. Its a great thing in life when you can actually take on someonelses' view on things and walk a day in their shoes... over the corpses of innocents...
