i once came in halfway through an evil campaign as a replacement player. it was a large group, and most of the players were LE or NE, but there was one CE character as well. the CE character was causing all kinds of problems for the DM and the rest of the group. after i sat in on a session, i rolled a character: a NE assassin, an enforcer of the international thieve's guild, and a worshipper of Mask. after the DM approved my character, he subtly suggested that i poison the CE character because his actions in particular were making things very hard on my PC's organization. i agreed, the CE character died an agonizing death after a meal one night, and we all continued the game without him. eventually, the campaign went into epic levels. the other PCs attempted to commit deicide (on Mystra, i think), and my PC was once again asked to intervene. fortunately, the Pcs turned on each other before my character was forced to kill them all, and the campaign was resolved. my point here is that after the CE character was out of the picture, the campaign held itself together for another 14 levels before the PCs became so power-hungry that things started breaking down. a campaign with nothing but LE characters, and maybe NE characters, can be quite fun.