When you think of the "golfer look", the immediate picture in a person's head is that of plaid pants, white shoes, and bright collared shirts.
This clich dress code that you see many golfers adhering to is not literally a requirement in order to play golf. Many courses have a very relaxed dress code for their players, while most private courses (and some public) do specify some sort of requirement for it's member's attire.
These dress codes are not meant to to make you wear funny looking clothes, but rather to provide an atmosphere of neatness and cleanliness. A simple pair of slacks, a decent collar shirt, and proper shoes is what makes up the average dress code at a private club.
Use Common Sense
You are least expected to wear a shirt and pants, or a skirt for women. Do not expect to be allowed on the golf course wearing only shorts, or a bathing suit for women.
Before you wonder why I bring this point up, yes - there are people out there who seem out of touch with etiquette and have showed up on the course with such low dress standards.