The bunkers I play day in and day out at my club have virtually flat bottoms, with a very slight rise in the sand on green side, followed by fairly steep, grass slopes up to the green. If your approach lands on the grass face of the bunker, and falls back into the bunker, you can be so close to the grass face that recovery is very difficult. The same result if your approach rolls into the bunker with some speed - it moves right up to the face. In short, it is always better to be back, away from the grass face, the further the better, in this recreational player's view . . . for example, 10 to 15 feet rather than one foot.