Bathroom Follies

I am working part time as a custodian at my church right now...well, I just got home, but I am under the employ of the church as a custodian. :D Anyway, I have noticed something odd about people that I have trouble understanding. Part of my work is to clean the bathrooms of the church. On occasion I have to do this while there are people in the building at an event. I will go into the bathroom, parking my cart so that it blocks the door entirely. The cart's length is almost exactly the same as the width of the door (I think the cart is about an inch or two longer), so there is no room to get past it into the bathroom. Yet, while I am cleaning, I will have people wander in and look at me nervously, as though wondering what I am doing.
Now, call me crazy if you will, but I would like to assume that if a janitor's cart is blocking the door, there should be a couple of things that can be assumed: 1. That probably means the janitor is cleaning; and 2. He likely wants you to stay out until he is finished. I can understand there being confusion if I have the cart beside the door but not impeding the way at all, but when it is in front of the door that should be a rather clear message, should it not? Yet I have people come in on me constantly. It is not so bad if a guy walks in on me because I am a guy. But when I am in the women's washroom, it really makes things awkward. Oddly enough, women are worse than the men. I don't know if the percentages of people that come in would be the same but more women come in because there are more women using the bathroom in general or what, but I have had twice as many women as men come into the bathroom while I am cleaning it.
What really gets me is that the people have to physically move the cart to get in, and then they are surprised when they see me in there. I wonder what is going through their minds as they move the cart ("golly, what a sloppy janitor - he left his cart in front of the door while he is off somewhere else cleaning"). Ladies, can you give me any hints as to why this might be? It's not like there is only the one bathroom - there is another set of bathrooms that can be used.
This has happened to me on at least three separate occasions since I began working for the church, but once was my own fault - I timed my cleaning poorly and the event let out while I was still in the ladies room, so people were coming to that bathroom because the other one had a line. But the other times there was no excuse.
I guess I just don't get it.
Also, the women leave their bathroom as dirty, or dirtier, than the mens.