Most people who ride the T have seen a sign that reads "Your tax dollars pay to keep this train clean, please do your part by removing your refuse," or something to that effect.
I have a couple of problems with this sign. Its purpose is to get people to take care of their trash and keep the train clean. But, it also tells you that not only is keeping the train clean someone else's problem, but that you're paying that person. There is a person who gets paid by the state -- by you, the train riding taxpayer -- to clean up after you. Please make their job easier by picking up your own trash!
To me, that is not a very compelling argument. Why should I pick up after myself? The way I see it, if I'm paying someone to clean up, why should I bother to keep it clean?
The sign should read, "If you picked up after yourselves the MBTA wouldn't have to pay someone to pick up after you and as a result your ride would be cheaper." That sign would motivate me to keep the train clean.
Also, what does it say about our society that we need a sign to remind us to be clean? Are we really that inconsiderate? Furthermore, the idea that all it takes is a simple sign to change our behavior suggests that we are weak-willed and easily swayed by even the slightest notion of authority.