My body is fairly odd in this regard.
My "on the way home from a drink-a-thon snack" was a McDonald's Big Mac meal. Washed down with a FourLoko or some other high-alcoholic sugary convenience-store cocktail.
I've done that twice since Paleo, and each time awoke no worse for wear except for the obvious negative issues from the drink (puffy face, cloudy head, and smelling like a dirty laundry hamper). That being said, most of my friends drink Guinness, and I myself love the stuff - which gives me a fairly strong lower GI reaction, so it could be I'm just not noticing.
However, there have been times where I've came home hungry, the wife may not have been expecting me, and bought pizza for her and the kid to share. I've eaten two slices, immediately had my sinuses lock up, and crapped my brains out for the next two days.
Now when I do have a drink, I tend to sleep very heavy. Perhaps my body is going into hyper recovery-mode while I sleep, and thus the damage is mitigated. Perhaps with the other toxins in my body (alcohol) my immune system is severely impaired fighting the alcohol and simply lets the other toxins "slide". Don't know. Don't risk it so I simply only really drink at social functions now - and while at those social functions I may relax my diet a little bit while staying gluten-free (corn tortillas, potatoes, oats in haggis on burns nights, etc) I make sure I'm fairly satiated before I bum a ride home.
Oddly enough, the last time I went out drinking with friends for a Birthday party, I drank an inordinate amount of strongbow cider and whiskey (about 6 boilermaker bombs in the span of 3 hours or so), had a plate of steak and french fries, and felt absolutely fantastic the next day. I guess I stayed sober enough to acknowledge I needed to stay away from gluten during my little bender.
To answer your question - if I'm drunk - damage seems milder than expected.
If I'm sober, and my diet is 100%, I have a reaction nothing short of catastrophic.