In reading the gathered wisdom of others via sites like Dragonsfoot, I gather that the general consensus seems to be that player characters should all get along and evil alignments are frowned upon.
I find myself wondering why? Sure, I’ve been involved in some games that became bitter feuds between players, but removing the choice (to be good or to be bad) from the players seems heavy handed. Sometimes it can be great fun to play a real villain… and sometimes a fight to the death between player characters can be more fun than just knocking down the monsters that the DM has set up to be conquered.
In literature, a novel in which the protagonist is flawed or even occasionally villainous is often called a picaresque story. Classic sword and sorcery heroes such as Leiber’s Fafhrd and Mouser or Vance’s Cugel the Clever are decidedly flawed heroes… maybe even REH’s Conan would qualify. Certainly D&D got its start with killing monsters in order to steal their treasure… the game was structured to reward those who were most proficient at killing and looting.