Here's a non-theoretical theoretical for everyone
I'm working in a very casual environment for a cabaret, this weekend. One of the Executive Producers is a friend of mine, actually my sister's roommate. The Exec. Prods., who are also both performers in the show, like to have a drink or two before the show and at intermission; this has never affected their performances in any negative way that I can tell. It's a very laid back show with very professional performers, and no safety issues beyond the normal issues you expect when a group of people gather in one place (people tripping over their own feet, etc.). Occasionaly, a group will have a drink together at the theatre, after the show. This is the second time I've worked for this group.
Last night, the Exec. Prod. who is my sister's roommate offered me a beer before the show. It was a micro-brew I had never tried before, and I like trying all sort of diferent beers. And, as this is a relaxed environment with others drinking before the show, I was tempted. Ultimately, I decided no, because, "Sometimes, in certain circumstances, it's okay," is a slippery slope I don't want to be on when it comes to alcohol and work, and you never know when some sort of strange disaster is going to happen when you need your full faculties (not that I really thought one beer was going to reduce my faculties!)
So, given that it's your Executive Producer offering you something to drink, would you have had one beer before the show?
Edited formatting of label-Rebbe