Ideally when swinging an iron, the iron should be equally flush to the ground, not having the toe in the air, or the heal when at impact.  This helps promote more consistent performance with your swing, helping to hit the ball on the sweet-spot of the iron, every time.  Having equipment that has not been tweaked to your individual unique swing, will make for many inconsistent hits. 

Tweak the club to match your swing, don't change your swing to hit the club!  It's not always the archer, but the arrow!