Mouldy Rye Butter
Dungeons and Dragons in general a game of heroic adventure. Even though your hero can be very mischievous and/or flawed, he or she must ultimately be on the good team.
“People often play D&D because it lets them, through their characters, do things they can’t do in real life — fight monsters, cast spells, defeat evil so that good can triumph. Some people play because D&D lets them run wild, wreaking havoc in towns and going on what amounts to crime sprees or betraying their allies. What they want in the game has nothing to do with heroic adventure, but with using the game rules to act out antisocial fantasies.”
- 4e Dungeon Master’s Guide p.32
My philosophy is to blur the line between player and character and make their experiences overlap as much as possible. You certainly don’t have to abide by this at all, but it has been my experience (time and time and time again) that completely running wild slows the game down and makes it less fun for the other players (not to mention the DM). Evil player characters are not allowed, and use chaotic PCs with discretion.