Still an over-simplification. The fact that alcohol or its metabolytes are present in sweat does not equal “flush[ing] toxins out of your system” The vast majority of these substances are eliminated through urine.
Flushing out is too strong a term for it. Your body is mostly water, with a circulatory system. So water soluble toxins end up all through your body (ionic strength, cell walls etc notwithstanding). Some of that water is used for sweating, lots more makes up the plasma that keeps your blood flowing, distributing those toxins to the brain and causing hangover symptoms. It also carries it to the liver, where further metabolic processing occurs, and your kidneys, which are designed to excrete the leftover waste. So sweating is a very minor part of the process, and toxin removal via sweat is incidental, in the same way that alcohol and metabolites escape the body via the lungs, but the lungs do not flush out alcohol from your system.
Drinking plenty of water does help, though (to replace lost fluids, dilute the metabolites, and help your kidneys), and sweating in a steam room probably promotes that. Also, the steam room gives you time to let your body finish the cleanup work. But the normal internal processes do the real work of processing toxins, and the steam room just makes you feel better.
Si
Thank you,
When I saw a quote from me pop up as I was scrolling I assumed it was someone not beleiving my pseudo FOAF story (the friends are real, but the people who did the smelling where FOAFs)
Thanks. I think this is my best argument. (See OP, I’m trying to argue that sweating DOES NOT flush out toxins.)
So, water soluble toxins are in your sweat, and may even be oderiforous, but intentional sweating only gets rid of a miniscule portion when compared to the normal excretory system.
You flush more toxins down the toilet than you flush in the steamroom. (which when put like that, kinda makes me glad we’re not all sloughing off real toxins in the steam room–“hey buddy, keep your toxins over in your area.”)
It’s possible. Ketotic breath (fruity, with acetone smell) is a well-known sign of Diabetic Ketoacidosis. AFAIK, someone in Alcoholic Ketoacidosis would present the same way. However, this wouldn’t include all heavy drinkers, by any means.
I think a more interesting question is whether or not sweating (in a sauna or similar) can increase the level of toxins in sweat, or if it’s just one of those things that your body does but can’t be made more efficient. That is, if the metabolites of alcohol are released at X rate in the sweat, can you increase that to X[sup]2[/sup], or even X+1, by sweating more, or not?
I have no answer, only questions. My general response to those wishing to purge toxins is “Why do you think you’re more toxic than your body can handle on its own?” I’ve never gotten a satisfactory answer in those not suffering from liver or kidney disease.
St. Urho, surely YOU have something to say on the subjects of saunas, right? 
No, cause the body does not do anything to put those toxins in the sweat - they are just there in the water used to make the sweat - if you sweat more, you’ll sweat out a bit more, but only in proportion to your sweating. And you only sweat out a fraction of the toxins and you can’t sweat too much - cause you die.
Alcohol is processed by the body at a constant rate - ~25ml per hour. But the metabolites are processed slower - thats why they hang about to give you a hangover for much longer that you are actually drunk.
Si
Sauna-use is strongly correlated with alcohol use, so I have no good answer to that. 
What explains the pungent body odour one experiences after eating spicy foods like garlic or curry?
My mother claims that about forty years ago my dad went on a heavy session of drinking red wine for several days, it was summertime, and he turned the bed linen a light pink where he had sweated into it.
I don’t like to ask my elderly father for confirmation of this, but I’ll take my mum’s word on it.