I find that unless your campaign is based around breaking the law, assassinating people, or bringing down legitimate organizations or kingdoms, having an adventuring group that is basically evil is counterproductive to getting anything done. If played true to those alignments, the pursuit of wealth and power through murder and mayhem soon gets old and the characters inevitably prey upon one another, essentially imploding the game. That's if they are doing their alignments justice. Unless everyone is LE, any kind of loyalty soon flies out the window.
Moral of my story? If I want a lasting campaign, I disallow evil PCs.