What I notice in all those photos is that, with the possible exception of the first one--the painting--all the sporrans are hanging at the right height for what's being worn, the style of the sporran, etc...I don't mean "two ox feet below the midline measurement of the wearer's third rib, excepting third tuesdays or during a lunar eclipse", rather that it's all visually balanced. Not sure of the right height? Look in a mirror. If it's under the dunlop, it's too low. If it looks like a fanny pack worn in the front, it's too high. If you think it's at a good height, go for a walk, and if it smacks you in the junk, then it's too low. Likewise, if if the strap falls off your butt, then the strap is too loose...which also happens to mean its too low.

FWIW, I've also noticed that if I'm wearing a baggy hoodie (any snowboarder has a closet full of them), I drop the sporran a little lower so it's more apparent beneath the hem of the hoodie...so...check the mirror, and mess with it until it looks "correct".