Many years ago the band I was in were filmed for a TV programme. We all had a few drinks beforehand to chill and because we played better that way anyway.
The show was never broadcast, and when I saw, but more importantly heard the tape I immediately knew why, we were appalling.
Where we thought drink loosened us up and made us play better what it did was loosen us up so all the timing and precision was lost.
Lesson learned for me, though I have to say to my shame I still played gigs drunk afterwards in both that and the next band.
In my last band (fast forward some time from the above, and to where I no longer drink alcohol) the other guys might have one drink beforehand but we always worked on the thought that people were paying to see us so we should provide the best performance possible, playing drunk would be short changing them.