Our biggest annoyance was soap. Soap bars disappeared, liquid soap made gigantic foam baths all over the bathroom/kitchen/hallway/kid's room. The solution was homemade foam soap; one part liquid soap, nine parts water. Even if they used the entire bottle, they only used 1/10 the ampunt of actual soap. And substantially less foam bath everywhere.
Ours was dish soap - once the kids starting washing dishes they were going through enormous amounts, so I started watering it way down.
OnE time we ran out, so DH picked up a bottle on the way home and gave it straight to the 16-yr old. She told me that she was afraid to use it.
Thought dad had gotten ripped off, that it was a fake soap. Either that, or it had gone bad. When I asked her why, she said it was all thick and weird.
Maybe this should be its own thread - Mustachian children's problems. Kids who think squashed TP is normal, can't recognize undiluted soap, and believe everyone washes baggies.