I worked in the babysitting room at an athletic facility, and per company policy, caregivers were not allowed to change a diaper with a BM...we had to go get the parent and then they had to leave their workout to come change Junior...how many times i heard, "oh just let him stay in it til i'm done"...really??? you expect us to deal with that stench while you work out and wont be back for an hour? Not to mention, no other kids will play near him cuz he stinks, and h'es stinking up the entire room...i'm sorry i had to drag you out of your workout, but there is more to think about here than just your waistline.............. I think its rotten a mother thinks more of her workout, than to come change her toddler who is sitting in his own poop.
EDIT: It is written in the gym policy that the PARENT has to come change diapers. They KNEW what they were signing, and KNEW they had to change their own kids, as it was reitterated when they visited the room.