I've flown twice with stonking hangovers.
Never ever again. It hurts and my performance was definitely below par. Whilst I was legal (8 hours before commencement of flight duties) I certainly wasn't ok.
Fatigue/tiredness has a big impact on performance too. This is where the focus of a lot of study and attention is now. FTL's are under threat from Europe.
I can see where Bar Shaker is coming from. 1 glass of wine ~5 hours before flight probably won't impair his/her flying ability in a normal situation. However, if there's an accident there'll be a blood test. If you're dead, there'll be an autopsy. If you're found to have alcohol in your blood then the insurance company won't pay. That's the real risk you're running. If you're happy with that, then fine. Also, the crash investigation team will conduct an enquiry. They will probably find out any way about the consumption of wine during that day.
I don't have any hard facts to hand but I am well aware that (for me) any consumption of alcohol will affect me that day. I won't risk drinking and riding my motorbike. Since the law is quite clear (for me) about drinking and flying I won't mix the two either. I fly for a living, I don't want to lose that.