Unfortunately that seems to be an inherent problem with Candace, at least the medium size.....my small Candace's aren't as prone to the 'side slouch'. I keep a purse insert in my bags just for that reason, to prevent the slouchies. Plus, keep them stuffed when not in use.
I'd be more alert to corner wear because a slouch is easier to 'fix'. I bought both my medium Candace's off ebay and coincidentally both sellers were TPF'ers and the bags were in excellent condition....one did have a bit of a slouch on one side, but I didn't let that bother me a bit since I've seen new ones with slouches.
I have been real lucky with my ebay purchases. I have unknowingly bought items from sellers that I later found out were TPF'ers......and all of the TPF'ers items were in excellent condition.