How to clean baby bottles

Just after I finished mopping up a mess around the changing table (I didn't know newborns were capable of spraying their feces over 2 meters) MIL takes the mop and the baby bottles and heads to the kitchen and starts to use the mob to clean the baby bottles.

Wife: "Mom, you're not going to use that mop to clean the baby bottles are you?"

MIL: "Sure, why not, mops are for cleaning." 

Wife:  "The mop is super dirty, you can't use it for cleaning the baby bottles."

MIL: "You don't know anything.  Mops are fine for cleaning bottles."