There doesn't seem to be any real dress code here. I've started dressing nicer this year, trying to more actively cultivate a professional image. It doesn't matter how inconspicuous I try to be, folks can always tell I'm a ref. It must be the bag.
Normally I'm in Dockers and a nice polo shirt. I have a nice looking, but inexpensive, pair of rubber-soled dress shoes. So I don't mind if I have to tramp through knee deep snow to get to the gym. I think it's more professional to dress at the game site, unless it's a JH. I've had one too many painful experiences with that.
But jeans seem to be just as acceptable here, and how my partner dresses hasn't usually been an indication of how the game will go. Well, unless he comes "dressed" to a HS game. Those guys turn out to be "interesting" partners a pretty high percentage of the time.
Volleyball is totally different. We all come dressed to our matches. Just a different culture.