1. People who don't put shopping carts in the corral, but just leave them in the middle of a parking space. I have actually called people on that in the parking lot - when I see them attempting to put the shopping cart into a parking space, I yell out the window at them to put it in the corral.
2. People who throw cigarette butts out the window. I sometimes walk to the gym, and there are literally thousands of butts on the side of the road. That's what an ashtray is for, buddy!
3. Related to this, people who litter in general. I once found a full cup of pop in a parking space when there was a trash can not fifty feet away. Exactly how lazy do you have to be to do something like that?
4. People who, when they are in a construction zone, drive all the way up to front of the line and then cut in. Nobody should ever let those people in, and maybe that would not happen.
5. People who do not say "thank you" when you open the door for them. When that happens, I just say "you're welcome" anyhow.
I could go on and on, but the bottom line is that there are plenty of thoughtless people out there who think that they are the only ones in the world, and it is someone else's job to clean up after them.