You're absolutely correct. It's unwise.
When I position, I present myself one of two ways.
1) In full uniform (and I will *not* drink).
2) Or in clothing that won't identify me as a crew member (and I *may* have a drink--but only if I'm deadheading into a rest period).
I agree that it's pretty risky these days to present oneself as a crewmember and then remove a few things (stripes and hat) and have a drink.
You're either on duty or off as far as the public is concerned and if you're off duty you should just "blend in"...
...and that's when my sweater (jumper) comes in very handy. Sort of like Superman's cape--but not really, I guess.
If I was the crewmember in question, in uniform but without the stripes or jacket, then I'd probably just have orange juice. It's better for you anyway.
