Cigarettes give me salt at the expense of health. Booze gives me health at the expense of salt. Do these effects balance out, or is there a net positive effect? In other words, can I sustain myself on cigarettes and alcohol and (apart from the last debuff) maintain maximum health and salt?
Yes, you can.
Cigarettes give you a higher amount of your salt than they make you lose HP. Alcohol gives you more/the equal amount (Couldn't get it confirmed) health than it makes you lose salt.
This allows you to effectively smoke and drink as much as you want, and staying healthy at the same time.
There are a two exceptions:
Absinthe (Fully increases Salts but decreases Health by half and instantly inebriates)
Flask of Unknown Booze (Fully increases Health but decreases Salts by half and instantly inebriates)