PLEASE ask before flipping the roll if the house you are visiting has either a cat or a toddler!!!
You see, they like to bat at the roll to make it spin, and they will bat at it downward. If you do that with an "over" installed roll, it will spool out onto the floor, but if the roll is "under" it will just spin around.
Trust me, you haven't lived until your cat slips into the bathroom during Christmas dinner and unspools your last roll onto the floor.