So, what exactly are we talking about?
Let say you report for duty at 0600. Last drink at 2200, using the 8 hour rule (regulations regarding alcohol and flying differs from company to company, where I work, the rule says 12 hours).
The average man burns 0.15 Promille
pr hour, so to be absolute sober, your promille at 2200 must be 1.2 or less. For you to be at 0.2 or less (this seems to be the industry standard in Europe), your promille must be 1.4 or less 8 hours before. 1.4, and NOT on the rise.
Now, 1.4 promille is not something you get after 2 glasses of wine or 2 pints of beer. At 1.4 promille you are fairly drunk.
I know there are exceptions to the rule, some burn faster, some burn less (like me). Your body mass, sex, amount of food eaten, etc, will affect how drunk you get. It's up to US to take these factors into account, and to be on the safe side.
Fatigue is very real, and very dangerous. Drunk the night before flying will not improve your fitness, even at 0 promille
Mouth rinse may trigger a breath test, but not a blood test.
The Swedish rule, with max 0.2 promille 8 hours BEFORE duty, means, in most cases, no drinking during layovers in Sweden. I don't like this rule, I think it's way over the top, but it's there. It's real. Beware!
As to alcohol being a booster for your performance, yes, it's true. Small amounts may calm your nerves and enhance performance with regards to certain precision sports, such as shooting, etc. If you need to calm your nerves before flying, maybe it's time to find another job?
And to you journos out there, it's not illegal to get your facts right before you start the press. People’s lives, careers, and reputations are at stake. Printing a microscopic apology at page 22, 4 weeks after you crucified someone on the front page, is simply not the way to go.