The best place I ever played, the guest policy was clearly delineated. It requested clothing changes, etc in the locker room only. And there was a list of things that were banned, which would include the garb in the OP. So, my arrival format was: golf gear with long pants; dress shoes; and a blazer I'd picked out which went well with the shirt and pants. My clubs were collected by the attendant at the curb, leaving me holding a small "golfer's gym bag" (with Taylor Made logo) which contained: golf shoes, extra socks, a neatly folded backup shirt (in case I needed a clean one for lunch), and a nice wooden hanger just in case I needed it. I didn't; nice wooden hangers were provided, like everything else.
Upon arrival I was on "the list" and shown straight to the locker room, where they had a row of lockers set up for guests. I stowed my things in there and was directed by the attendant to the point where I could find my host and the caddies for the day.
The guest policy helped me perfectly anticipate and set up for the experience, as a good guest policy should. The OP's friend must follow such a document to the letter.