Here's Sheldon's take, which I've found to be true in my experience. Obviously, other factors (bar height in relation to saddle, saddle model, rider geometry - sit bone spacing, rider position, etc) can influence each person's own experience.

Angle

The angle of the saddle should be pretty close to horizontal. Some men prefer the front to be slightly higher than the rear; some women prefer the front slightly lower than the rear, but extreme angles should be avoided.
If the saddle is nosed up too far, it is likely to increase pressure on the soft tissues, and cause all sorts of problems.
If the saddle is tilted down in front, the rider will tend to slide forward onto the narrower part of the saddle. Women who are riding on saddles that were designed for men frequently tilt their saddles down. This will relieve some of the discomfort from the saddle itself, but creates new problems: The downward slope of the saddle causes the rider to tend to slide forward, and this can only be counteracted by pressure on the hands. Thus, poorly-angled saddles often are the cause of wrist, shoulder and neck problems, due to carrying too much of the rider's weight on the hands.
The angle and the front-back position are both adjusted by the clamp on the seatpost.