Peter,
At first, I was tempted to say that when you start getting over 45 degrees, you've got to start asking questions.
But then again I thought of holes that angle more than 90 that don't feel gimmicky, and some that angle far less than 30 that feel gimmicky.
So I guess the real "test of gimmickry" is
* What is the reason for the dogleg? Going around a lake, a ravine, a forest, etc... All seem in our minds to be "valid" reasons and we are more willing to accept the dogleg as natural. Going around a housing development or a practice range cannot be view is such a positive light.
* What protects the inside of the dogleg? The ocean, for example, would be accepted. Internal O.B. would be gimmicky.
*What sort of distances can you hit your shots? The shorter the distance that you can hit the ball (before running out of fairway), the more gimmicky it becomes.
*How does it fit the contours of the land? Obviously, if it goes against the slope (i.e. balls kicking towards the outside of the corner), it will be less "natural".
* What's the angle of the dogleg? The sharper it is, the more gimmicky the hole might seem to be (depending on the answers to the above).
So, according to this hastily devised "test", what are good doglegs and bad doglegs?
* Good: 18th at Sawgrass; 13th at Augusta National
* Bad: 9th at Katchewano - nearly exact same hole as 18th at Sawgrass, but internal O.B. rather than lake protects adjoining hole. 4th at Orford - 90+ degree dogleg left par 5. 160 yards to reach first turning point, O.B. line painted in fairway past dogleg that says "if your tee shot lands beyond this line, you're O.B."