Age aside these models aren't that great when the waist is bent, the bumm and crotch distorts too much. they look great standing but seriously that bent over shot above makes her rear end look like the end of a chicken leg bone:
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I've mentioned this before that not all models/rigs are going to look good in every pose and it's worth the effort to have a second model/rig when the pose breaks the rig. Just make a copy and adjust the mesh/weighting so that ass looks good when in those poses.