Our cats are sack-lovers too! Maya always checks every bag with groceries that enters our house! Well.... , I don't think she is looking for monsters in there, she just wants to be sure if meowmie bought enough catfood and a supply of snacks . Inka is the one who loves get into empty sacks, just checking if there isn't an evil creature in it. I have seen her run around like a Caped Crusader too! That is so hilarious!! When something gets ataached around her tail, she always needs me to take it off .
Zazou doesn't have any "sack-experience" yet. Maya and Inka will teach her that, I have NO doubt about that