I just prefer to see any part of it hanging loose so that it is easy to unroll.
I like it to dispense overhand, but then we had this car a while back who thought it was the greatest thing to completely unspool the entire roll onto the floor. So, for a while we switched to underhand until he passed away. Now, it is back to overhand.
What we do for our cars (cats).
Over, except when the roll is behind and to the left of the toilet. Then under.
The actual Patent shows the correct way..overhand (a drawing on the patent)