I had Mexican food last night, again with beer (mostly to test my prophylactic concoction again). Another success!
After dinner, I logged in to my e-mail and discovered my 23andMe results were ready, and I spent most of the evening browsing through them. According to 23andMe, I have no facial flush from alcohol, and I am at high risk for Celiac disease. I have to look into these results more closely to find out if they have any plausible real connection to "beer face," but at least I think a good working hypothesis right now is that any flushing after drinking is more likely from a non-inebriation reaction.