Unbalanced mafia games

[Elmo]

I personally don't mind playing swingy (or indeed, unbalanced) games as long as I know about it up front. I generally assume that the mod thinks a setup is balanced and non-swingy unless they say otherwise, so I think you should explicitly notify players and make sure they understand what's going on when they're signing up. I don't know of any established etiquette, though.