Golf club fitters are similar to swing instructors in the sense that each one has their own idea on how to best perform their job. Just as you can go to three different swing instructors and get three different opinions on how to improve your swing, you can go to three different fitters and get three different opinions about the golf clubs you should be playing.
With golf clubs the fit is EVERYTHING, so you need to choose your fitter carefully.
A competent fitter can clearly articulate his objectives. When fitting a golfer, I have three goals. I refer to them as my "Three C's".
COMFORT.
Thew grip's size and taper should feel COMFORTABLE in the player's hands. Each shaft length should allow the player to COMFORTABLY assume an effective address position. And when swinging, the player should feel COMFORTABLE with the club's balance, as well as the weight and flex of the shaft.
COMPOSITION.
The set COMPOSITION (the combination of wedges, irons, hybrids, and fairway metals) should provide the player with playable trajectories, functional yardage gaps, and a progressive series of predictable carry distances.
COMPENSATION.
The specifications of each club should compensate for the player's most common miss. The goal is to reduce the severity of that miss: to help the player turn a percentage of his below average shots into average shots.