Pugsley:
Actually, when I made PS for California Grill last year, and was told "Smart casual" dress, I thought I'd have some fun and ask what exactly that meant. Turns out the person who took my PS couldn't really tell me-- "Something Nice"-- was the best she could come up with. I then called California Grill direct and asked to speak with the manager on duty that evening. We had a nice chat--again, he hemmed and hawed about what "Smart casual" meant. So I asked-'What would NOT meet that suggested mode of attire"?
The answer--tank tops for men, bathing suits, flip-flops instead of shoes. And that was it.