Yes, I too agree that littering is a great offence to the
environment and the inability to use toilet facilities cleanly
reflects badly on our society, that is why I take heed that I
myself do not do such a thing. So since emptying spent oils into
the sewer system is also the wrong thing to do, shouldn't we, as
responsible adults, do our part by disposing of it properly?
I am guessing you tell your friends who do not think litter and
dirty toilets is wrong how much "harm" it is; we are doing the same
thing here, which is to bring to attention and focus on a practice
that you might have miscontrued as acceptable, where in reality it
is not.