> In fact I'd wager that's why sin taxes are effective, because the largest consumers of cigarettes, soda, etc are poor people

I'm not a fan of sin taxes. To me, taxes are for funding the government and should not be a form of punishment. If you punish people with taxes or try to change their behavior then you're just breeding resentment against taxes. Then the population votes to decrease taxes every chance they get because they're associated with punishment. Also, isn't a sin tax basically a fine with no chance to plead your case?