When it's a Tennis Dress.
I found the Calvin Klein tennis dress at left, a couple of weeks ago, and immediately thought of golf. After all, it has a collar, and it's longer than much of what's worn on the LPGA tour these days.
I definitely like the convenience of one piece instead of several (fewer moving parts = fewer pieces to... um... misplace) Lately though its been hard to find those one piece wonders in golf apparel shops and sections. So tennis seemed the next best thing. And in this case it worked out just fine.